Thermodynamics

Question 1

Maximum work that could be secured by expanding the gas over a given pressure range is the __________ work. A. isothermal B. adiabatic C. isentropic D. none of these

Answer 1

A. isothermal

Question 2

Internal energy change of a system over one complete cycle in a cyclic process is A. zero B. +ve C. -ve D. dependent on the path

Answer 2

A. zero

Question 3

Heating of water under atmospheric pressure is an __________ process. A. isochoric B. isobaric C. adiabatic D. isothermal

Answer 3

B. isobaric

Question 4

Van Laar equation deals with the activity co-efficients in A. binary solutions B. ternary solutions C. azeotropic mixture only D. none of these

Answer 4

A. binary solutions

Question 5

High __________ is an undesirable property for a good refrigerant. A. specific heat B. latent heat of vaporisation C. viscosity D. specific vapor volume

Answer 5

C. viscosity

Question 6

Solubility of a substance which dissolves with an increase in volume and liberation of heat will be favoured by the A. low pressure and high temperature. B. low pressure and low temperature. C. high pressure and low temperature. D. high pressure and high temperature.

Answer 6

B. low pressure and low temperature.

Question 7

Entropy is a measure of the __________ of a system. A. disorder B. orderly behaviour C. temperature changes only D. none of these

Answer 7

A. disorder

Question 8

A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is A. zero B. positive C. negative D. none of these

Answer 8

C. negative

Question 9

Fundamental principle of refrigeration is based on the __________ law of thermodynamics. A. zeroth B. first C. second D. third

Answer 9

C. second

Question 10

For a spontaneous process, free energy A. is zero B. increases C. decreases whereas the entropy increases D. and entropy both decrease

Answer 10

C. decreases whereas the entropy increases

Question 11

A refrigeration cycle is a reversed heat engine. Which of the following has the maximum value of the co-efficient of performance (COP) for a given refrigeration effect ? A. Vapor compression cycle using expansion valve. B. Air refrigeration cycle. C. Vapor compression cycle using expansion engine. D. Carnot refrigeration cycle.

Answer 11

D. Carnot refrigeration cycle.

Question 12

In a working refrigerator, the value of COP is always A. 0 B. < 0 C. < 1 D. > 1

Answer 12

D. > 1

Question 13

A refrigerator may be termed as a A. heat pump B. heat engine C. Carnot engine D. none of these

Answer 13

A. heat pump

Question 14

For a stable phase at constant pressure and temperature, the fugacity of each component in a binary system __________ as its mole fraction increases. A. decreases B. increases C. remains same D. decreases linearly

Answer 14

B. increases

Question 15

Which of the following is not an intensive property ? A. Chemical potential B. Surface tension C. Heat capacity D. None of these

Answer 15

C. Heat capacity

Question 16

Out of the following refrigration cycles, which one has the minimum COP (Co-efficient of performance)? A. Air cycle B. Carnot cycle C. Ordinary vapour compression cycle D. Vapour compression with a reversible expansion engine

Answer 16

A. Air cycle

Question 17

Measurement of thermodynamic property of temperature is facilitated by __________ law of thermodynamics. A. 1st B. zeroth C. 3rd D. none of these

Answer 17

B. zeroth

Question 18

The theoretical minimum work required to separate one mole of a liquid mixture at 1 atm, containing 50 mole % each of n- heptane and n- octane into pure compounds each at 1 atm is A. -2 RT ln 0.5 B. -RT ln 0.5 C. 0.5 RT D. 2 RT

Answer 18

B. -RT ln 0.5

Question 19

Keeping the pressure constant, to double the volume of a given mass of an ideal gas at 27°C, the temperature should be raised to __________ °C. A. 270 B. 327 C. 300 D. 540

Answer 19

B. 327

Question 20

Isobaric process means a constant process. A. temperature B. pressure C. volume D. entropy

Answer 20

B. pressure

Question 21

No work is done by the system, when a reaction occurs at constant A. volume B. temperature C. pressure D. none of these

Answer 21

A. volume

Question 22

If the vapour pressure at two temperatures of a solid phase in equilibrium with its liquid phase are known, then the latent heat of fusion can be calculated by the A. Maxwell’s equation B. Clayperon-Claussius equation C. Van Laar equation D. Nernst Heat Theorem

Answer 22

B. Clayperon-Claussius equation

Question 23

The freezing point of a liquid decreases when the pressure is increased, if the liquid __________ while freezing. A. contracts B. expands C. does not change in volume D. either (a), (b) or (c)

Answer 23

A. contracts

Question 24

“At the absolute zero temperature, the entropy of every perfectly crystalline substance becomes zero”. This follows from the A. third law of thermodynamics B. second law of thermodynamics C. Nernst heat theorem D. Maxwell’s relations

Answer 24

A. third law of thermodynamics

Question 25

During Joule-Thomson expansion of gases A. enthalpy remains constant. B. entropy remains constant. C. temperature remains constant. D. none of these.

Answer 25

A. enthalpy remains constant.

Question 26

The accentric factor of a materical, ‘ω’, is defined as ω = -log10(Pr^sat)Tr^-1 = 0.7, where, Pr^sat = reduced vapor pressure, Tr = reduced temperature. The value of accentric factor is always A. > 2 B. < 1 C. > 1 D. < 3

Answer 26

B. < 1

Question 27

Degress of freedom at triple point will be A. 0 B. 1 C. 2 D. 3

Answer 27

A. 0

Question 28

“Law of corresponding states” says that A. , two different gases behave similarly, if their reduced properties (i.e. P, V and T) are same. B. the surface of separation (i. e. the meniscus) between liquid and vapour phase disappears at the critical temperature. C. no gas can be liquified above the critical temperature, howsoever high the pressure may be. D. the molar heat of energy of gas at constant volume should be nearly constant (about 3 calories).

Answer 28

A. , two different gases behave similarly, if their reduced properties (i.e. P, V and T) are same.

Question 29

Linde gas liquefaction process employs cooling A. by throttling B. by expansion in an engine C. at constant pressure D. none of these

Answer 29

A. by throttling

Question 30

Pick out the wrong statement pertaining to the decomposition of PCl5 represented by, PCl5 ⇌ PCl3 + Cl2.Degree of dissociation of PCl5 will A. decrease on addition of Cl2. B. increase on addition of an inert gas at constant pressure. C. decrease on increasing the pressure of the system. D. none of these

Answer 30

D. none of these

Question 31

Boyle’s law for gases states that A. (1) , when temperature is constant. B. (1) , when temperature & mass of the gas remain constant. C. P ∝ V, at constant temperature & mass of the gas. D. P/V = constant, for any gas.

Answer 31

B. (1) , when temperature & mass of the gas remain constant.

Question 32

1st law of thermodynamics is nothing but the law of conservation of A. momentum B. mass C. energy D. none of these

Answer 32

C. energy

Question 33

In a reversible chemical reaction (where, Δx = number of moles of products-number of moles of reactants ) A. addition of inert gas favours the forward reaction, when Δx is positive. B. pressure has no effect on equilibrium, when Δn = 0. C. addition of inert gas has no effect on the equilibrium constant at constant volume for any value of Δx (+ ve, - ve) or zero). D. all of these

Answer 33

D. all of these

Question 34

Out of the following refrigeration cycles, which one has maximum COP ? A. Air cycle B. Carnot cycle C. Ordinary vapor compression cycle D. Vapor compression with a reversible expansion engine

Answer 34

B. Carnot cycle

Question 35

Pick out the correct statement: A. In an isothermal system, irreversible work is more than reversible work. B. Under reversible conditions, the adiabatic work is less than isothermal work. C. Heat, work, enthalpy and entropy are all ‘state functions’. D. Matter and energy can not be exchanged with the surroundings in a closed system.

Answer 35

B. Under reversible conditions, the adiabatic work is less than isothermal work.

Question 36

In any spontaneous process, A. only F decreases B. only A decreases C. both F and A decreases D. both F and A increase

Answer 36

C. both F and A decreases

Question 37

Which of the following is a thermodynamic property of a system ? A. Concentration B. Mass C. Temperature D. Entropy

Answer 37

D. Entropy

Question 38

Equilibrium constant decreases as the temperature A. increases, for an exothermic reaction. B. decreases, for an exothermic reaction. C. increases, for an endothermic reaction. D. none of these.

Answer 38

A. increases, for an exothermic reaction.

Question 39

The expression, (1) , gives the free energy change A. with pressure changes at constant temperature. B. under reversible isothermal volume change. C. during heating of an ideal gas. D. during cooling of an ideal gas.

Answer 39

A. with pressure changes at constant temperature.

Question 40

All gases during throttling process at atmospheric temperature and pressure show a cooling effect except A. CO2 B. H2 C. O2 D. N2

Answer 40

B. H2

Question 41

Compressibility factor for almost all the gases are approximately same at the same A. pressure and temperature. B. reduced pressure and reduced temperature. C. critical pressure and critical temperature. D. none of these.

Answer 41

B. reduced pressure and reduced temperature.

Question 42

Pick out the wrong statement. A. Activity co-efficient is dimensionless. B. In case of an ideal gas, the fagacity is equal to its pressure. C. In a mixture of ideal gases, the fugacity of a component is equal to the partial pressure of the component. D. The fugacity co-efficient is zero for an ideal gas.

Answer 42

D. The fugacity co-efficient is zero for an ideal gas.

Question 43

The co-efficient of performance (COP) of a refrigerating system, which is its index of performance, is defined as the ratio of useful refrigeration to the net work. The units of __________ and COP are the same. A. kinematic viscosity B. work C. temperature D. none of these

Answer 43

D. none of these

Question 44

The chemical potential of a component (μi) of a phase is the amount by which its capacity for doing all work, barring work of expansion is increased per unit amount of sustance added for an infinitesimal addition at constant temperature and pressure. It is given by A. B. C. D. all of these

Answer 44

D. all of these

Question 45

In jet refrigerators, the refrigerating fluid is practically always A. water B. ammonia C. freon D. brine

Answer 45

A. water

Question 46

Water on heating from 1 to 4°C A. contracts B. expands C. has same volume D. may contract or expand

Answer 46

A. contracts

Question 47

Pick out the correct statement. A. Compression ratio of an Otto engine is comparatively higher than a diesel engine. B. Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio. C. Otto engine efficiency decreases with the rise in compression ratio, due to decrease in work produced per quantity of heat. D. Diesel engine normally operates at lower compression ratio than an Otto engine for an equal output of work.

Answer 47

B. Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio.

Question 48

When pressure is applied on the system, ice<—->water, then A. equilibrium can not be established. B. more ice will be formed. C. more water will be formed. D. evaporation of water will take place.

Answer 48

C. more water will be formed.

Question 49

Partial molar free energy of an element A in solution is same as its A. chemical potential B. activity C. fugacity D. activity co-efficient

Answer 49

A. chemical potential

Question 50

Free energy change at equilibrium is A. zero B. positive C. negative D. indeterminate

Answer 50

A. zero

Question 51

The temperature at which both liquid and gas phases are identical, is called the __________ point. A. critical B. triple C. freezing D. boiling

Answer 51

A. critical

Question 52

What is the value of ln y (where y = activity co-efficient) for ideal gases ? A. Zero B. Unity C. Infinity D. Negative

Answer 52

A. Zero

Question 53

A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system A. its internal energy (U) decreases and its entropy (S) increases. B. U and S both decreases C. U decreases but S is constant. D. U is constant but S decreases.

Answer 53

B. U and S both decreases

Question 54

Which is not a refrigerant ? A. SO2 B. NH3 C. CCl2F2 D. C2H4Cl2

Answer 54

D. C2H4Cl2

Question 55

The partial pressure of each constituent present in an alloy is __________ the total vapor pressure exerted by the alloy. A. less than B. equal to C. more than D. either (b) or (c); depends on the type of alloy

Answer 55

A. less than

Question 56

The four properties of a system viz. P, V, T, S are related by __________ equation. A. Gibbs-Duhem B. Gibbs-Helmholtz C. Maxwell’s D. none of these

Answer 56

C. Maxwell’s

Question 57

If the pressure on 100 c.c. of air is halved, then its volume (at the same temperature) would be __________ c.c. A. 100 B. 50 C. 205 D. 200

Answer 57

D. 200

Question 58

Pick out the wrong statement. A. Cp of monoatomic gases such as metallic vapor is about 5 kcal/kg.atom. B. The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state. C. There is an increase in entropy, when a spontaneous change occurs in an isolated system. D. At absolute zero temperature, the heat capacity for many pure crystalline substances is zero.

Answer 58

B. The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state.

Question 59

The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are A. zero B. one C. two D. three

Answer 59

B. one

Question 60

Any substance above its critical temperature exists as A. saturated vapour B. solid C. gas D. liquid

Answer 60

C. gas

Question 61

Which of the following decreases with increase in pressure ? A. Melting point of ice B. Melting point of wax C. Boiling point of liquids D. none of these

Answer 61

A. Melting point of ice

Question 62

Isentropic process means a constant __________ process. A. enthalpy B. pressure C. entropy . D. none of these

Answer 62

C. entropy .

Question 63

(1) is the mathematical expression A. Joule-Thomson co-efficient. B. specific heat at constant pressure (Cp). C. co-efficient of thermal expansion. D. specific heat at constant volume (CV).

Answer 63

C. co-efficient of thermal expansion.

Question 64

In case of steady flow compression polytropic process (PVn = constant), the work done on air is the lowest, when A. n = y = 1.4 B. n = 0 C. n = 1 D. n = 1.66

Answer 64

C. n = 1

Question 65

A liquid under pressure greater than its vapour pressure for the temperature involved is called a __________ liquid. A. subcooled B. saturated C. non-solidifiable D. none of these

Answer 65

A. subcooled

Question 66

For a real gas, the chemical potential is given by A. RT dlnP B. RT dlnf C. R dlnf D. none of these

Answer 66

B. RT dlnf

Question 67

At absolute zero temperature, all substances have the same A. heat capacity B. crystalline structure C. entropy D. none of these

Answer 67

A. heat capacity

Question 68

Lowering of condenser temperature (keeping the evaporator temperature constant) in case of vapour compression refrigeration system results in A. increased COP. B. same COP. C. decreased COP. D. increased or decreased COP ; depending upon the type of refrigerant.

Answer 68

A. increased COP.

Question 69

Pick out the correct statement. A. If an insoluble gas is passed through a volatile liquid placed in a perfectly insulated container, the temperature of the liquid will increase. B. A process is irreversible as long as Δ S for the system is greater than zero. C. The mechanical work done by a system is always equal to P.dV. D. The heat of formation of a compound is defined as the heat of reaction leading to the formation of the compound from its reactants.

Answer 69

D. The heat of formation of a compound is defined as the heat of reaction leading to the formation of the compound from its reactants.

Question 70

Grams of butane (C4H10) formed by the liquefaction of 448 litres of the gas (measured at (STP) would be A. 580 B. 640 C. 1160 D. data insufficient; can’t be computed

Answer 70

C. 1160

Question 71

The thermodynamic law, PVy = constant, is not applicable in case of A. ideal compression of air. B. free expansion of an ideal gas. C. adiabatic expansion of steam in a turbine. D. adiabatic compression of a perfect gas.

Answer 71

B. free expansion of an ideal gas.

Question 72

Mollier diagram is a plot of A. temperature vs. enthalpy B. temperature vs. enthalpy C. entropy vs. enthalpy D. temperature vs. internal energy

Answer 72

C. entropy vs. enthalpy

Question 73

is the mathematical expression for A. CV B. enthalpy change C. free energy change D. none of these

Answer 73

D. none of these

Question 74

The activity of an ideal gas is numerically __________ its pressure. A. more than B. less than C. equal to D. data insufficient, can’t be predicted

Answer 74

C. equal to

Question 75

Specific heat of a gas for a reversible adiabatic process is A. negative B. zero C. infinity D. none of these

Answer 75

B. zero

Question 76

When a gas in a vessel expands, its internal energy decreases. The process involved is A. reversible B. irreversible C. isothermal D. adiabatic

Answer 76

A. reversible

Question 77

A system is said to be isopiestic, if there is no __________ change. A. temperature B. pressure C. volume D. none of these

Answer 77

B. pressure

Question 78

In a turbine, the fluid expands almost A. isothermally B. isobarically C. adiabatically D. none of these

Answer 78

C. adiabatically

Question 79

The unity of Planck’s constant ‘h’ in the equation, E = hv is A. J/s B. J.S C. J/kmol D. kmol/J

Answer 79

B. J.S

Question 80

Specific/molar Gibbs free energy for a pure substance does not change during A. sublimation B. vaporisation C. melting D. either (a), (b) or (c)

Answer 80

D. either (a), (b) or (c)

Question 81

Refrigeration capacity of a household refrigerator may be round about __________ tons. A. 0.15 B. 1.5 C. 4.5 D. 6.5

Answer 81

A. 0.15

Question 82

(1) is the mathematical expression for A. CV B. entropy change C. Gibbs free energy D. none of these

Answer 82

D. none of these

Question 83

An ideal gas is taken around the cycle ABCA as shown in P-V diagram below :The work done by the gas during the cycle is equal to A. 12 P1V1 B. 6 P1 V1 C. 3 P1V1 D. P1 V1

Answer 83

C. 3 P1V1

Question 84

In polytropic process (PVn = constant), if n = 1; it means a/an __________ process. A. adiabatic B. reversible C. isothermal D. none of these

Answer 84

C. isothermal

Question 85

The melting point of paraffin wax (which contracts on solidification) __________ with pressure rise. A. increases B. decreases C. remains unchanged D. decreases linearly

Answer 85

A. increases

Question 86

Co-efficient of Performance (COP) of a refrigerator is the ratio of the A. work required to refrigeration obtained. B. refrigeration obtained to the work required. C. lower to higher temperature. D. higher to lower temperature.

Answer 86

B. refrigeration obtained to the work required.

Question 87

A solid metallic block weighing 5 kg has an initial temperature of 500°C. 40 kg of water initially at 25°C is contained in a perfectly insulated tank. The metallic block is brought into contact with water. Both of them come to equilibrium. Specific heat of block material is 0.4 kJ.kg^-1. K^-1. Ignoring the effect of expansion and contraction and also the heat capacity to tank, the total entropy change in kJ.kg^-1 , K^-1 is A. -1.87 B. 0 C. 1.26 D. 3.91

Answer 87

B. 0

Question 88

dW and dq are not the exact differential, because q and W are A. state functions B. path functions C. intensive properties D. extensive properties

Answer 88

B. path functions

Question 89

Activity co-efficient is a measure of the A. departure from ideal solution behaviour. B. departure of gas phase from idea] gas law. C. vapour pressure of liquid. D. none of these.

Answer 89

A. departure from ideal solution behaviour.

Question 90

While dissolving a gas into a liquid at a constant temperature, the ratio of the concentration of the gas in the solution phase and in the gaseous phase is A. infinity B. unity C. constant D. negative

Answer 90

C. constant

Question 91

Which of the following units is not present in both the vapor compression refrigeration system and absorption refrigeration system ? A. Expansion valve B. Condenser C. Refrigerator D. Compressor

Answer 91

D. Compressor

Question 92

For an isothermal reversible compression of an ideal gas A. only ΔE = 0 B. only ΔH =0 C. ΔE = ΔH = 0 D. dQ = dE

Answer 92

C. ΔE = ΔH = 0

Question 93

Melting of ice exemplifies a/an A. adiabatic process. B. endothermic reaction. C. exothermic reaction. D. process involving a chemical reaction.

Answer 93

B. endothermic reaction.

Question 94

A refrigeration cycle is the same as a __________ cycle, A. turbine B. heat engine C. reversed heat engine D. none of these

Answer 94

C. reversed heat engine

Question 95

At __________ point, all the three phases (i.e.solid, liquid and gas) co-exist. A. eutcetic B. triple C. plait D. critical

Answer 95

B. triple

Question 96

Kopp’s rule is used to calculate the heat capacity of A. solids B. liquids C. gases D. all of these

Answer 96

A. solids

Question 97

__________ explains the equilibrium constant for any chemical reaction. A. Henry’s law B. Law of mass action C. Hess’s law D. none of these

Answer 97

B. Law of mass action

Question 98

Which of the following is not a reversible process ? A. Expansion of an ideal gas against constant pressure. B. Atmospheric pressure vaporisation of water at 100°C. C. Solution of NaCl in water at 50°C. D. None of these.

Answer 98

C. Solution of NaCl in water at 50°C.

Question 99

Pick out the wrong statement. A. A closed system does not permit exchange of mass with its surroundings but may permit exchange of energy. B. An open system permits exchange of both mass and energy with its surroundings. C. The term microstate is used to characterise an individual, whereas macro-state is used to designate a group of micro-states with common characteristics. D. none of the above.

Answer 99

D. none of the above.

Question 100

Which of the following exemplifies an adiabatic process ? A. Melting of ice. B. Condensation of alcohol vapor. C. Sudden bursting of a cycle tube. D. Evaporation of water.

Answer 100

C. Sudden bursting of a cycle tube.

Question 101

Entropy, which is a measure of the disorder of a system is A. independent of pressure. B. independent of temperature. C. zero at absolute zero temperature for a perfect crystalline substance. D. all of these

Answer 101

C. zero at absolute zero temperature for a perfect crystalline substance.

Question 102

Critical temperature is defined as the temperature above which a gas will A. not liquify (barring exceptions). B. immediately liquify. C. never liquify however high the pressure may be. D. none of these.

Answer 102

C. never liquify however high the pressure may be.

Question 103

The standard Gibbs free energy change of a reaction depends on the equilibrium A. pressure B. temperature C. composition D. all of these

Answer 103

B. temperature

Question 104

Gibbs-Duhem equation relates composition in liquid phase and the __________ at constant temperature & pressure. A. fugacity B. partial pressure C. activity co-efficient D. (a), (b), and (c)

Answer 104

D. (a), (b), and (c)

Question 105

In an ideal solution, the activity of a component equals its A. mole fraction. B. fugacity at the same temperature and pressure. C. partial pressure. D. none of these.

Answer 105

A. mole fraction.

Question 106

A gas has a volume of 27.3 c.c. at 0°C. Its volume at 10°C (if pressure remains unchanged) will be __________ c.c. A. 2.73 B. 28.3 C. 273 D. 283

Answer 106

B. 28.3

Question 107

Clayperon equation deals with the A. rate of change of vapour pressure with temperature. B. effect of an inert gas on vapour pressure. C. calculation of ΔF for spontaneous phase change. D. temperature dependence of heat of phase transition.

Answer 107

A. rate of change of vapour pressure with temperature.

Question 108

Which of the following is an undesirable characteristics of a refrigerant ? A. It should be non-explosive. B. It should have a sub-atmospheric vapor pressure at the temperature in refrigerator coils. C. Its vapor pressure at the condenser temperature should be very high. D. None of these.

Answer 108

B. It should have a sub-atmospheric vapor pressure at the temperature in refrigerator coils.

Question 109

“The rate at which a substance reacts is proportional to its active mass and the rate of a chemical reaction is proportional to the product of active masses of the reacting substances”. This is the A. Lewis-Randall rule. B. statement of Vant-Hoff equation. C. Le-Chatelier’s principle. D. none of these.

Answer 109

D. none of these.

Question 110

What is the ratio of adiabatic compressibility to isothermal compressibility ? A. 1 B. < 1 C. > 1 D.&raquo_space; 1

Answer 110

B. < 1

Question 111

The absolute entropy for all crystalline substances at absolute zero temperature is A. zero B. negative C. more than zero D. indeterminate

Answer 111

A. zero

Question 112

Pick out the wrong statement. A. Phase rule variables are intensive properties. B. Heat and work are both state function. C. The work done by expansion of a gas in vacuum is zero. D. CP and CV are state function.

Answer 112

B. Heat and work are both state function.

Question 113

Compressibility factor of a gas is A. not a function of its pressure. B. not a function of its nature. C. not a function of its temperature. D. unity, if it follows PV = nRT.

Answer 113

D. unity, if it follows PV = nRT.

Question 114

Which of the following is not an extensive property ? A. Free energy B. Entropy C. Refractive index D. None of these

Answer 114

C. Refractive index

Question 115

Forward reaction will be favoured for the exothermic reaction, represented by CO + H2O ⇌ CO2 + H2, by A. low temperature and high pressure. B. low temperature and low pressure. C. high temperature and high pressure. D. high temperature and low pressure.

Answer 115

A. low temperature and high pressure.

Question 116

Enthalpy of a gas depends upon its A. temperature B. mass C. volume D. pressure

Answer 116

A. temperature

Question 117

When dilute aqueous solutions of two salts are mixed, the process is associated with A. decrease in temperature. B. increase in temperature. C. no change in temperature. D. change in temperature which is a function of composition.

Answer 117

B. increase in temperature.

Question 118

Pick out the correct statement. A. Like internal energy and enthalphy, the absolute value of standard entropy for elementary substances is zero. B. Melting of ice involves increase in enthalpy and a decrease in randomness. C. The internal energy of an ideal gas depends only on its pressure. D. Maximum work is done under reversible conditions.

Answer 118

D. Maximum work is done under reversible conditions.

Question 119

Chemical engineering thermodynamics is concerned with the __________ in/of chemical processes. A. reaction mechanism B. calculation of rates C. energy transformation from one form to the another D. none of these

Answer 119

C. energy transformation from one form to the another

Question 120

An isolated system can exchange __________ with its surroundings. A. matter B. energy C. neither matter nor energy D. both matter and energy

Answer 120

C. neither matter nor energy

Question 121

Requisites of a reversible process is that the A. system and surroundings pressure be equal. B. friction in the system should be absent. C. system and surroundings temperature be equal. D. none of these.

Answer 121

B. friction in the system should be absent.

Question 122

Fugacity is most helpful in A. representing actual behaviour of real gases. B. representing actual behaviour of ideal gases. C. the study of chemical equilibria involving gases at atmospheric pressure. D. none of these

Answer 122

A. representing actual behaviour of real gases.

Question 123

The energy of activation of exothermic reaction is A. zero. B. negative. C. very large compared to that for en-dothermic reaction. D. not possible to predict.

Answer 123

D. not possible to predict.

Question 124

Pick out the wrong statement. A. The chemical potential of a pure substance depends upon the temperature and pressure. B. The chemical potential of a component in a system is directly proportional to the escaping tendency of that component. C. The chemical potential of ith species (μi) in an ideal gas mixture approaches zero as the pressure or mole fraction (xi) tends to be zero at constant temperature. D. The chemical potential of species ‘i’ in the mixture (μi) is mathematically represented as, (1) , where, n, ni and nj respectively denote the total number of moles, moles of ith species and all mole numbers except ith species. ‘G’ is Gibbs molar free energy.

Answer 124

C. The chemical potential of ith species (μi) in an ideal gas mixture approaches zero as the pressure or mole fraction (xi) tends to be zero at constant temperature.

Question 125

In the reaction; N2 + O2 (1) 2NO, increasing the pressure will result in A. shifting the equilibrium towards right, B. shifting the equilibrium towards left. C. no change in equilibrium condition. D. none of these.

Answer 125

C. no change in equilibrium condition.

Question 126

A cyclic engine exchanges heat with two reservoirs maintained at 100 and 300°C respectively. The maximum work (in J) that can be obtained from 1000 J of heat extracted from the hot reservoir is A. 349 B. 651 C. 667 D. 1000

Answer 126

A. 349

Question 127

Pick out the wrong statement. A. Trouton’s ratio of non-polar liquids is calculated using Kistyakowasky equation. B. Thermal efficiency of a Carnot engine is always less than 1. C. An equation relating pressure, volume and temperature of a gas is called ideal gas equation. D. none of these.

Answer 127

C. An equation relating pressure, volume and temperature of a gas is called ideal gas equation.

Question 128

When a gas is subjected to adiabatic expansion, it gets cooled due to A. decrease in velocity. B. decrease in temperature. C. decrease in kinetic energy. D. energy spent in doing work.

Answer 128

D. energy spent in doing work.

Question 129

Joule-Thomson effect i.e., a throttling process is a constant __________ process. A. entropy B. temperature C. internal energy D. enthalpy

Answer 129

D. enthalpy

Question 130

In the equation, PV^n = Constant, if the value of n = 0, then it represents a reversible __________ process. A. isobaric B. isothermal C. isentropic D. isometric

Answer 130

A. isobaric

Question 131

Work done in an adiabatic process between two states depends on the A. rate of heat transmission B. initial state only C. end states only D. none of these

Answer 131

C. end states only

Question 132

The number of degree of freedom for an azeotropic mixture of ethanol and water in vapour-liquid equilibrium, is A. 3 B. 1 C. 2 D. 0

Answer 132

B. 1

Question 133

The internal energy of an ideal gas is a function of its __________ only. A. molecular size B. volume C. pressure D. temperature

Answer 133

D. temperature

Question 134

At constant temperature and pressure, for one mole of a pure substance, the ratio of the free energy to the chemical potential is A. zero B. one C. infinity D. negative

Answer 134

B. one

Question 135

The change in __________ is equal to the reversible work for compression in steady state flow process under isothermal condition. A. internal energy B. enthalpy C. Gibbs free energy D. Helmholtz free energy

Answer 135

C. Gibbs free energy

Question 136

Work done is a A. property of the system B. path function C. point function D. state description of a system

Answer 136

B. path function

Question 137

Extensive properties of a thermodynamic system depend upon the __________ of the system. A. specific volume B. temperature C. mass D. pressure

Answer 137

C. mass

Question 138

Near their critical temperatures, all gases occupy volumes __________ that of the ideal gas. A. less than B. same as C. more than D. half

Answer 138

A. less than

Question 139

The free energy change for a chemical reaction is given by (where, K = equilibrium constant) A. RT lnK B. -RT lnK C. -R lnK D. T lnK

Answer 139

B. -RT lnK

Question 140

Free energy, fugacity and activity co-efficient are all affected by change in the temperature. The fugacity co-efficient of a gas at constant pressure ____with the increase of reduced temperature. A. decreases B. increases C. remains constant D. decreases logarithmically

Answer 140

B. increases

Question 141

In the reaction, H2 +I2 ⇌ 2HI, addition of an inert gas will A. increase the partial pressure of H2. B. increase the partial pressure of I2. C. increase the total pressure and hence shift the equilibrium towards the right. D. not effect the equilibrium conditions

Answer 141

D. not effect the equilibrium conditions

Question 142

What is the number of degrees of freedom for liquid water in equilibrium with a mixture of nitrogen and water vapor ? A. 2 B. 0 C. 3 D. 1

Answer 142

A. 2

Question 143

The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called the __________ temperature. A. critical B. Boyle C. inversion D. reduced

Answer 143

B. Boyle

Question 144

If the molar heat capacities (Cp or Cv) of the reactants and products of a chemical reaction are identical, then, with the increase in temperature, the heat of reaction will A. increase B. decrease C. remain unaltered D. increase or decrease ; depends on the particular reaction

Answer 144

C. remain unaltered

Question 145

All gases above its inversion temperature, in a throttling process will show A. a heating effect. B. no change in temperature. C. a cooling effect. D. either (a) or (c).

Answer 145

A. a heating effect.

Question 146

First law of thermodynamics is mathematically stated as A. dQ = dE + dW B. dQ = dE - dW C. dE = dQ + dW D. dW = dQ + dE

Answer 146

A. dQ = dE + dW

Question 147

Pick out the wrong statement. A. Surface tension of a substance vanishes at critical point, as there is no distinction between liquid and vapour phases at its critical point. B. Entropy of a system decreases with the evolution of heat. C. Change of internal energy is negative for exothermic reactions. D. The accentric factor for all materials is always more than one.

Answer 147

D. The accentric factor for all materials is always more than one.

Question 148

Translational kinetic energy of molecules of an ideal gas is proportional to (where, T = absolute temperature of the gas ) A. T B. √T C. T^2 D. 1/√T

Answer 148

A. T

Question 149

Equation which relates pressure, volume and temperature of a gas is called the A. equation of state B. Gibbs Duhem equation C. ideal gas equation D. none of these

Answer 149

A. equation of state

Question 150

Claussius-Clayperon equation gives accurate result, when the A. vapour pressure is relatively low and the temperature does not vary over wide limits. B. vapour obeys the ideal gas law and the latent heat of vaporisation is constant. C. volume in the liquid state is negligible compared with that in the vapour state. D. all of these

Answer 150

D. all of these

Question 151

The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called __________ temperature. A. Boyle B. inversion C. critical D. reduced

Answer 151

A. Boyle

Question 152

For a single component two phase mixture, the number of independent variable properties are A. two B. one C. zero D. three

Answer 152

B. one

Question 153

__________ law of thermodynamics ascertains the direction of a particular spontaneous process. A. Zeroth B. First C. Second D. Third

Answer 153

C. Second

Question 154

At normal boiling point, molar entropy of vaporisation is __________ Joule/K°.mole. A. 72 B. 92 C. 142 D. 192

Answer 154

B. 92

Question 155

For an ideal solution, the value of activity co-efficient is A. 0 B. 1 C. < 1 D. > 1

Answer 155

B. 1

Question 156

The expression, nCv(T2 - T1), is for the __________ of an ideal gas. A. work done under adiabatic condition B. co-efficient of thermal expansion C. compressibility D. none of these

Answer 156

A. work done under adiabatic condition

Question 157

Which of the following is a widely used refrigerant in vapour compression refrigeration system (using large centrifugal compressor)? A. Freon B. Liquid sulphur dioxide C. Methyl chloride D. Ammonia

Answer 157

A. Freon

Question 158

Internal energy is equal to the heat absorbed in case of a/an __________ process. A. constant volume B. polytropic C. adiabatic D. constant pressure

Answer 158

A. constant volume

Question 159

The first law of thermodynamics is a restatement of the law of conservation of A. mass B. energy C. momentum D. none of these

Answer 159

A. mass

Question 160

Joule-Thomson co-efficient for a perfect gas is A. zero B. positive C. negative D. none of these

Answer 160

B. positive

Question 161

In an adiabatic process, the A. heat transfer is zero. B. temperature change is zero. C. work done is a path function. D. enthalpy remains constant.

Answer 161

A. heat transfer is zero.

Question 162

A nozzle is a device, which A. increases kinetic energy and decreases pressure. B. reduces kinetic energy and increases pressure. C. reduces both kinetic energy and pressure. D. increases both kinetic energy and pressure.

Answer 162

A. increases kinetic energy and decreases pressure.

Question 163

Duringthe phase transition, __________ changes. A. pressure B. volume C. temperature D. all of these

Answer 163

B. volume

Question 164

The work done in an adiabatic change in a particular gas depends upon changes in the __________ only. A. temperature B. specific heat C. volume D. pressure

Answer 164

A. temperature

Question 165

In an isothermal process on an ideal gas, the pressure increases by 0.5 percent. The volume decreases by about __________ percent. A. 0.25 B. 0.5 C. 0.75 D. 1

Answer 165

B. 0.5

Question 166

Which of the following is not a unit of the equilibrium constant Kp? (where, Δx = number of moles of products number of moles of reactants) A. (atm)Δx, when Δx is negative B. (atm)Δx, when Δx is positive C. Dimensionless, when Δx = 0 D. (atm)Δx2, when Δx > 0

Answer 166

D. (atm)Δx2, when Δx > 0

Question 167

Pick out the correct statement. A. The available energy in an isolated system for all irreversible (real) processes decreases. B. The efficiency of a Carnot engine increases, if the sink temperature is decreased. C. The reversible work for compression in non-flow process under isothermal condition is the change in Helmholtz free energy. D. all of these

Answer 167

D. all of these

Question 168

Partial molal quantities are important in the study of A. ideal gases B. ideal solutions C. non-ideal mixtures D. a pure component

Answer 168

C. non-ideal mixtures

Question 169

Number of degrees of freedom for a three phase system in equilibrium comprising of three non-reacting chemical species is A. 2 B. 0 C. 1 D. 3

Answer 169

A. 2

Question 170

Critical solution temperature (or the con-solute temperature) for partially miscible liquids (e.g., phenol-water) is the minimum temperature at which A. a homogeneous solution (say of phenol water) is formed. B. mutual solubility of the two liquids shows a decreasing trend. C. two liquids are completely separated into two layers. D. none of these.

Answer 170

A. a homogeneous solution (say of phenol water) is formed.

Question 171

Enthalpy ‘H’ is defined as A. H = E - PV B. H = F - TS C. H - E = PV D. none of these

Answer 171

C. H - E = PV

Question 172

One ton of refrigeration is defined as the heat rate corresponding to melting of one ton of ice in one A. hour B. day C. minute D. second

Answer 172

B. day

Question 173

__________ functions are exemplified by heat and work. A. Path B. Point C. State D. none of these

Answer 173

A. Path

Question 174

In an irreversible process A. Tds = dE - dW = 0 B. dE - dW - Tds = 0 C. Tds - dE + dW< 0 D. Tds - dT + dW< 0

Answer 174

C. Tds - dE + dW< 0

Question 175

What is the number of degree of freedom for a system of two miscible non-reacting species in vapor-liquid equilibrium forming an azeotrope ? A. 3 B. 2 C. 1 D. 0

Answer 175

C. 1

Question 176

The entropy change in a reversible isothermal process, when an ideal gas expands to four times its initial volume is A. R loge 4 B. R log10 4 C. Cv log10 4 D. Cv loge 4

Answer 176

A. R loge 4

Question 177

PVγ = Constant (where, γ = Cp/Cv) is valid for a/an __________ process. A. isothermal B. isentropic C. isobaric D. adiabatic

Answer 177

D. adiabatic

Question 178

Claude gas liquefaction process employs cooling A. at constant pressure. B. by throttling. C. by expansion in an engine. D. none of these.

Answer 178

C. by expansion in an engine.

Question 179

Which of the following will increase the volume of a real gas by four times ? A. Doubling the absolute temperature as well as pressure of the gas. B. Reducing pressure to one fourth at constant temperature. C. Reducing temperature to one fourth at constant pressure. D. Reducing the temperature to half and doubling the pressure.

Answer 179

B. Reducing pressure to one fourth at constant temperature.

Question 180

Pick out the wrong statement. A. A refriferation cycle violates the second law of thermadynamics. B. Refrigeration cycle is normally represented by a temperature vs. entropy plot. C. In a refrigerator, work required decreases as the temperature of the refrigerator and the temperature at which heat is rejected increases. D. One ton of refrigeration is equivalent to the rate of heat absorption equal to 3.53 kW.

Answer 180

A. A refriferation cycle violates the second law of thermadynamics.

Question 181

The equation, PV = nRT, is best obeyed by gases at A. low pressure & high temperature. B. high pressure & low temperature. C. low pressure & low temperature. D. none of these.

Answer 181

A. low pressure & high temperature.

Question 182

Internal energy of an element at 1 atm and 25° C is __________ kcal/kg.mole. A. 0 B. 273 C. 25 D. none of these

Answer 182

A. 0

Question 183

Which of the following liquid metals has the highest thermal conductivity ? A. Molten sodium B. Molten lead C. Mercury D. Molten potassium

Answer 183

A. Molten sodium

Question 184

Which of the following has the least thermal efficiency ? A. Steam engine B. Carnot engine C. Diesel engine D. Otto engine

Answer 184

A. Steam engine

Question 185

Joule-Thomson Co-efficient at any point on the inversion curve is A. ∞ B. + ve C. 0 D. -ve

Answer 185

C. 0

Question 186

Pick out the wrong statement. A. The values of (1) are zero for a real gas at its critical point. B. Heat transferred is equal to the change in the enthalpy of the system, for a constant pressure, non-flow, mechanically reversible process. C. Thermal efficiency of a Carnot engine depends upon the properties of the working fluid besides the source & sink temperatures. D. During a reversible adiabatic process, the entropy of a substance remains constant.

Answer 186

C. Thermal efficiency of a Carnot engine depends upon the properties of the working fluid besides the source & sink temperatures.

Question 187

Number of components (C), phase (P) and degrees of freedom (F) are related by Gibbs phase rule as A. P + F - C = 2 B. C = P - F + 2 C. F = C - P - 2 D. P = F - C - 2

Answer 187

A. P + F - C = 2

Question 188

The value of Cp & Cv respectively for monoatomic gases in Kcal/kg Mole . °K are A. 5 & 3 B. 3.987 & 1.987 C. 1.987 & 0.66 D. 0.66 & 1.987

Answer 188

A. 5 & 3

Question 189

(1) is the mathematical expression for A. specific heat at constant pressure (Cp). B. specific heat at constant volume (Cv). C. Joule-Thompson co-efficient. D. none of these.

Answer 189

C. Joule-Thompson co-efficient.

Question 190

In case of a close thermodynamic system, there is __________ across the boundaries. A. no heat and mass transfer B. no mass transfer but heat transfer C. mass and energy transfer D. none of these

Answer 190

B. no mass transfer but heat transfer

Question 191

During a reversible isothermal expansion of an ideal gas, the entropy change is A. +ve B. 0 C. -ve D. ∞

Answer 191

A. +ve

Question 192

As the temperature is lowered towards the absolute zero, the value of (1), then approaches A. unity B. zero C. that of the heat of reaction D. infinity

Answer 192

B. zero

Question 193

Which of the following is not affected by temperature changes ? A. Fugacity B. Activity co-efficient C. Free energy D. None of these

Answer 193

D. None of these

Question 194

For an ideal gas, the activity co-efficient is A. directly proportional to pressure. B. inversely proportional to pressure. C. unity at all pressures. D. none of these.

Answer 194

C. unity at all pressures.

Question 195

Those solutions in which there is no volume change upon mixing the components in the liquid state and which, when diluted do not undergo any heat change (i.e. heat of dilution is zero), are called __________ solutions. A. ideal B. real C. isotonic D. none of these

Answer 195

A. ideal

Question 196

Generation of heat by friction is an example of a/an __________ change. A. isothermal B. irreversible C. adiabatic D. reversible

Answer 196

B. irreversible

Question 197

A domestic refrigerator has a/an __________ cooled condenser. A. water B. air C. evaporative D. gas

Answer 197

B. air

Question 198

The compressibility factor of a gas is given by (where, V1 = actual volume of the gas V2 = gas volume predicted by ideal gas law ) A. V1/V2 B. V2/V1 C. V1-V2 D. V1.V2

Answer 198

A. V1/V2

Question 199

If we increase the pressure on a substance (which is at its triple point), then the triple point A. increases B. decreases C. remains unchanged D. may increase or decrease ; depends on the substance

Answer 199

C. remains unchanged

Question 200

In an ideal refrigeration cycle, the change in internal energy of the fluid is A. +ve B. -ve C. 0 D. either of the above three ; depends on the nature of refrigerant.

Answer 200

C. 0

Question 201

Free energy A. decreases in all spontaneous (or irreversible) processes. B. change during a spontaneous process has a negative value. C. remains unchanged in reversible processes carried at constant temperature and pressure. D. all of these

Answer 201

D. all of these

Question 202

“If different processes are used to bring about the same chemical reaction, the enthalpy change is same for all of them”. This is __________ law. A. Hess’s B. Kirchoff’s C. Lavoisier and Laplace D. none of these

Answer 202

A. Hess’s

Question 203

Fugacity is a measure of the A. escaping tendencies of the same substance in different phases of a system. B. relative volatility of a mixture of two miscible liquids. C. behaviour of ideal gases. D. none of these.

Answer 203

A. escaping tendencies of the same substance in different phases of a system.

Question 204

The quantitative effect of temperature on chemical equilibrium is given by the A. Vant-Hoff equation. B. Le-Chatelier’s principle. C. Arhenius equation. D. none of these.

Answer 204

A. Vant-Hoff equation.

Question 205

For an irreversible process involving only pressure-volume work A. (dF)T, p <0 B. (dF)T, p = 0 C. (dF)T, p > 0 D. (dA)T, v >0

Answer 205

A. (dF)T, p <0

Question 206

Ideal refrigeration cycle is A. same as Carnot cycle. B. same as reverse Carnot cycle. C. dependent on the refrigerant’s properties. D. the least efficient of all refrigeration processes.

Answer 206

B. same as reverse Carnot cycle.

Question 207

The following heat engine produces power of 100000 kW. The heat engine operates between 800 K and 300 K. It has a thermal efficiency equal to 50% of that of the Carnot engine for the same temperature. The rate at which heat is absorbed from the hot reservoir is A. 100, 000 kW B. 160, 000 kW C. 200, 000 kW D. 320, 000 kW

Answer 207

D. 320, 000 kW

Question 208

The enthalpy change when ammonia gas is dissolved in water is called the heat of A. solution B. formation C. dilution D. combustion

Answer 208

A. solution

Question 209

The value of Joule-Thomson co-efficient, in case where cooling occurs after the throttling process is A. 0 B. ∞ C. +ve D. -ve

Answer 209

C. +ve

Question 210

The specific heat of saturated water vapour at 100°C is A. ∞ B. -ve C. 0 D. +ve

Answer 210

B. -ve

Question 211

For a multicomponent system, the term chemical potential is equivalent to the A. molal concentration difference. B. molar free energy. C. partial molar free energy. D. molar free energy change.

Answer 211

C. partial molar free energy.

Question 212

The change in Gibbs freee energy for vaporisation of a pure substance is A. positive B. negative C. zero D. may be positive or negative

Answer 212

C. zero

Question 213

Critical compressibility factor for all substances A. are more or less constant (vary from 0.2 to 0.3). B. vary as square of the absolute temperature. C. vary as square of the absolute pressure. D. none of these.

Answer 213

A. are more or less constant (vary from 0.2 to 0.3).

Question 214

What is the degree of freedom for two mis-cible (non-reacting) substances in vapor-liquid equilibrium forming an azeotrope ? A. 0 B. 1 C. 2 D. 3

Answer 214

C. 2

Question 215

For a given substance at a specified temperature, activity is __________ to fugacity. A. directly proportional B. inversely proportional C. equal D. none of these

Answer 215

A. directly proportional

Question 216

In case of vapour compression refrigeration system, elevating the evaporator temperature (keeping the condenser temperature constant) results in A. enhanced COP. B. decreased COP. C. no change in the value of COP. D. increased or decreased COP ; depending upon the type of refrigerant.

Answer 216

A. enhanced COP.

Question 217

For water at 300°C, it has a vapour pressure 8592.7 kPa and fugacity 6738.9 kPa Under these conditions, one mole of water in liquid phase has a volume of 25.28 cm^3 and that in vapour phase in 391.1 cm^3.Fugacity of water (in kPa) at 9000 kPa will be A. 6738.9 B. 6753.5 C. 7058.3 D. 9000

Answer 217

B. 6753.5

Question 218

As the temperature is lowered towards the absolute zero, the value of the quantity approaches A. zero B. unity C. infinity D. none of these

Answer 218

A. zero

Question 219

If the heat of solution of an ideal gas in a liquid is negative, then its solubility at a given partial pressure varies with the temperature as A. solubility increases as temperature increases. B. solubility increases as temperature decreases. C. solubility is independent of temperature. D. solubility increases or decreases with temperature depending on the Gibbs free energy change of solution.

Answer 219

B. solubility increases as temperature decreases.

Question 220

In case of a reversible process (following pv^n = constant), work obtained for trebling the volume (v1 = 1 m^3 and v2 3 m^3 ) is max imum, when the value of ‘n’ is A. 0 B. 1 C. y = 1.44 D. 1.66

Answer 220

A. 0

Question 221

The Carnot co-efficient of performance (COP) of a domestic air conditioner compared to a household refrigerator is A. less B. more C. same D. dependent on climatic conditions

Answer 221

A. less

Question 222

The unit of fugacity is the same as that of the A. pressure B. temperature C. volume D. molar concentration

Answer 222

A. pressure

Question 223

Filling of gas from a high pressure cylinder into small bottles is an example of a/an __________ process. A. equilibrium B. adiabatic C. steady D. unsteady

Answer 223

D. unsteady

Question 224

A large iceberg melts at the base, but not at the top, because of the reason that A. ice at the base contains impurities which lowers its melting point. B. due to the high pressure at the base, its melting point reduces. C. the iceberg remains in a warmer condition at the base. D. all of these

Answer 224

B. due to the high pressure at the base, its melting point reduces.

Question 225

At the critical point of a substance A. the surface tension vanishes. B. liquid and vapour have the same density. C. there is no distinction between liquid and vapour phases. D. all of these

Answer 225

D. all of these

Question 226

A system undergoes a change from a given initial state to a given final state either by an irreversible process or by a reversible process, then(where, Δ S1 and Δ SR are the entropy changes of the system for the irreversible and reversible processes respectively) A. Δ S1 is always < Δ SR B. Δ S1 is sometimes > Δ SR C. Δ S1 is always > Δ SR D. Δ S1 is always = Δ SR

Answer 226

C. Δ S1 is always > Δ SR

Question 227

What is the value of Joule-Thomson co-efficient for an ideal gas ? A. +ve B. -ve C. 0 D. ∞

Answer 227

C. 0

Question 228

A two stage compressor is used to compress an ideal gas. The gas is cooled to the initial temperature after each stage. The intermediate pressure for the minimum total work requirement should be equal to the __________ mean of P1 and P2.(where, P1 and P2 are initial and final pressures respectively) A. logarithmic B. arithmetic C. geometric D. harmonic

Answer 228

C. geometric

Question 229

y = specific heat ratio of an ideal gas is equal to A. Cp/Cv B. Cp/(CP-R) C. 1 + (R/CV) D. all of these

Answer 229

D. all of these

Question 230

Consider the process A & B shown in the figure given below (1) In this case, it is possilbe that A. both the processes are adiabatic. B. both the processes are isothermal. C. process A is isothermal while B is adiabatic. D. process A is adiabatic while B is isothermal.

Answer 230

C. process A is isothermal while B is adiabatic.

Question 231

Gibbs free energy of a pure fluid approaches __________ as the pressure tends to zero at constant temperature. A. infinity B. minus infinity C. zero D. none of these

Answer 231

B. minus infinity

Question 232

As the entropy of the universe is increasing, day by day, the work producing capacity of a heat engine is A. not changed B. decreasing C. increasing D. data sufficient, can’t be predicted

Answer 232

B. decreasing

Question 233

An irreversible process A. is the analog of linear frictionless motion in machines. B. is an idealised visualisation of behaviour of a system. C. yields the maximum amount of work. D. yields an amount of work less than that of a reversible process.

Answer 233

D. yields an amount of work less than that of a reversible process.

Question 234

The expression for the work done for a reversible polytropic process can be used to obtain the expression for work done for all processes, except reversible __________ process. A. isobaric B. isothermal C. adiabatic D. none of these

Answer 234

B. isothermal

Question 235

Free energy change of mixing two liquid substances is a function of the A. concentration of the constituents only. B. quantities of the constituents only. C. temperature only. D. all of these

Answer 235

D. all of these

Question 236

Pick out the wrong statement. A. System (of partially miscible liquid pairs), in which the mutual solubility increases with rise in temperature, are said to possess an upper consolute temperature. B. Systems, in which the mutual solubility increases with decrease in temperature, are said to possess lower consolute temperature. C. Nicotine-water system shows both an upper as well as a lower consolute temperature, implying that they are partially miscible between these two limiting temperatures. D. none of these

Answer 236

D. none of these

Question 237

The total change in the enthalpy of a system is independent of the A. number of intermediate chemical reactions involved. B. pressure and temperature. C. state of combination and aggregation in the beginning and at the end of the reaction. D. none of these.

Answer 237

A. number of intermediate chemical reactions involved.

Question 238

Number of phases in a colloidal system are A. 1 B. 2 C. 3 D. 4

Answer 238

B. 2

Question 239

Free energy changes for two reaction mechanism ‘X’ and ‘Y are respectively - 15 and - 5 units. It implies that X is A. slower than Y B. faster than Y C. three times slower than Y D. three times faster than Y

Answer 239

B. faster than Y

Question 240

Vapour which is at a pressure smaller than the saturation pressure for the temperature involved is called a __________ vapour. A. superheated B. desuperheated C. non-condensable D. none of these

Answer 240

A. superheated

Question 241

At equilibrium condition, the chemical potential of a material in different phases in contact with each other is equal. The chemical potential for a real gas (μ) is given by(where, μ = standard chemical potential at unit fugacity (f° = 1 atm.) and the gas behaves ideally.) A. μ° + RT ln f B. μ°+ R lnf C. μ° + T lnf D. μ° + R/T lnf

Answer 241

A. μ° + RT ln f

Question 242

The kinetic energy of gas molecule is zero at A. 0°C B. 273°C C. 100°C D. -273°C

Answer 242

D. -273°C

Question 243

Which of the following is not an intensive property ? A. Volume B. Density C. Temperature D. Pressure

Answer 243

A. Volume

Question 244

The necessary and sufficient condition for equilibrium between two phases is A. the concentration of each component should be same in the two phases. B. the temperature of each phase should be same. C. the pressure should be same in the two phases. D. the chemical potential of each component should be same in the two phases.

Answer 244

D. the chemical potential of each component should be same in the two phases.

Question 245

Specific volume of an ideal gas is A. equal to its density. B. the reciprocal of its density. C. proportional to pressure. D. none of these.

Answer 245

B. the reciprocal of its density.

Question 246

Pick out the extensive property out of the following. A. Surface tension B. Free energy C. Specific heat D. Refractive index

Answer 246

B. Free energy

Question 247

Entropy change of the reaction, H2O(liquid) H2O(gas), is termed as the enthalpy of A. solution B. vaporisation C. formation D. formation

Answer 247

B. vaporisation

Question 248

Which law of the thermodynamics provids basis for measuring the thermodynamic property ? A. First law B. Zeroth law C. Third law D. Second law

Answer 248

B. Zeroth law

Question 249

Gibbs free energy per mole for a pure substance is equal to the A. latent heat of vaporisation B. chemical potential C. molal boiling point D. heat capacity

Answer 249

B. chemical potential

Question 250

Gibbs free energy at constant pressure and temperature under equilibrium conditions is A. ∞ B. 0 C. maximum D. minimum

Answer 250

D. minimum

Question 251

With increase in pressure (above atmospheric pressure), the Cp of a gas A. increases B. decreases C. remains unchanged D. first decreases and then increases

Answer 251

A. increases

Question 252

A change in state involving a decrease in entropy can be spontaneous, only if A. it is exothermic. B. it is isenthalpic. C. it takes place isothermally. D. it takes place at constant volume.

Answer 252

A. it is exothermic.

Question 253

Joule-Thomson co-efficient which is defined as, (1) , changes sign at a temperature known as inversion temperature. The value of Joule-Thomson co-efficient at inversion temperature is A. 0 B. ∞ C. +ve D. -ve

Answer 253

A. 0

Question 254

__________ calorimeter is normally used for measuring the dryness fraction of steam, when it is very low. A. Bucket B. Throttling C. Separating D. A combination of separating & throttling

Answer 254

D. A combination of separating & throttling

Question 255

The amount of heat required to decompose a compound into its elements is __________ the heat of formation of that compound from its elements. A. less than B. more than C. same as D. not related to

Answer 255

C. same as

Question 256

For a constant volume process A. dE = CpdT B. dE = CvdT C. dQ = dE + pdV D. dW = pdV

Answer 256

B. dE = CvdT

Question 257

In case of the decomposition of hydroiodic acid (2HI ⇌ H2 + I2), addition of H2 (at equilibrium condition) will A. increase the partial pressure of I2. B. decrease the partial pressure of HI. C. diminish the degree of dissociation of HI. D. none of these.

Answer 257

C. diminish the degree of dissociation of HI.

Question 258

In any spontaneous process, the __________ free energy decreases. A. Helmholtz B. Gibbs C. both a & b D. neither ‘a’ nor ‘b’

Answer 258

C. both a & b

Question 259

The equation DU = Tds - PdV is applicable to infinitesimal changes occuring in A. an open system of constant composition. B. a closed system of constant composition. C. an open system with changes in composition. D. a closed system with changes in composition.

Answer 259

D. a closed system with changes in composition.

Question 260

Heat is added at constant temperature in an ideal __________ cycle. A. Stirling B. Brayton C. Rankine D. none of these

Answer 260

A. Stirling

Question 261

Pick out the correct equation relating ‘F’ and ‘A’. A. F = A + PV B. F = E + A C. F = A - TS D. F = A + TS

Answer 261

A. F = A + PV

Question 262

In a reversible process A. Tds = dE + dW B. dE - dW = Tds C. dW - dE = Tds D. Tds - dW + dE >0

Answer 262

A. Tds = dE + dW

Question 263

Cv for an ideal gas A. does not depend upon temperature. B. is independent of pressure only. C. is independent of volume only. D. is independent of both pressure and volume.

Answer 263

D. is independent of both pressure and volume.

Question 264

In a homogeneous solution, the activity co-efficient of a component depends upon the A. pressure B. composition C. temperature D. all of these

Answer 264

D. all of these

Question 265

Pick out the wrong statement: A. The expansion of a gas in vacuum is an irreversible process. B. An isometric process is a constant pressure process. C. Entropy change for a reversible adiabatic process is zero. D. Free energy change for a spontaneous process is negative.

Answer 265

B. An isometric process is a constant pressure process.

Question 266

With increase in compression ratio, the efficiency of the otto engine A. increases B. decreases C. remains constant D. increases linearly

Answer 266

A. increases

Question 267

The chemical potential of any constituent of an ideal solution depends on the __________ of the solution. A. temperature B. pressure C. composition D. all of these

Answer 267

D. all of these

Question 268

Fugacity and pressure are numerically equal, when the gas is A. in standard state B. at high pressure C. at low temperature D. in ideal state

Answer 268

D. in ideal state

Question 269

Refrigerants commonly used for domestic refrigerators are A. ethyl chloride or methyle chloride B. freon-12 C. propane D. NH3 or CO2.

Answer 269

A. ethyl chloride or methyle chloride

Question 270

Absolute zero temperature signifies the A. minimum temperature attainable. B. temperature of the heat reservoir to which a Carnot engine rejects all the heat that is taken in. C. temperature of the heat reservoir to which a Carnot engine rejects no heat. D. none of these.

Answer 270

C. temperature of the heat reservoir to which a Carnot engine rejects no heat.

Question 271

Specific __________ does not change during a phase change (e.g. sublimation, melting, vaporisation etc.). A. entropy B. internal energy C. enthalpy D. Gibbs free energy

Answer 271

D. Gibbs free energy

Question 272

Heat of formation of an element in its standard state is A. 0 B. < 0 C. > 0 D. a function of pressure

Answer 272

A. 0

Question 273

The equation relating E, P, V and T which is true for all substanes under all conditions is given by (1) .This equation is called the A. Maxwell’s equation. B. thermodynamic equation of state. C. equation of state. D. Redlich-Kwong equation of state.

Answer 273

B. thermodynamic equation of state.

Question 274

For an exothremic reaction A. only enthalpy change (ΔH) is negative. B. only internal energy change (ΔE) is negative. C. both ΔH and ΔE are negative. D. enthalpy change is zero.

Answer 274

C. both ΔH and ΔE are negative.

Question 275

Pick out the wrong statement. A. An ideal liquid or solid solution is defined as one in which each component obeys Raoult’s law. B. If Raoult’s law is applied to one component of a binary mixture ; Henry’s law or Raoult’s law is applied to the other component also. C. Henry’s law is rigorously correct in the limit of infinite dilution. D. none of these.

Answer 275

D. none of these.

Question 276

The shape of T-S diagram for Carnot Cycle is a A. rectangle B. rhombus C. trapezoid D. circle

Answer 276

A. rectangle

Question 277

For an isothermal process, the internal energy of a gas A. increases B. decreases C. remains unchanged D. data insufficient, can’t be predicted

Answer 277

C. remains unchanged

Question 278

In the equation, PVn = constant, if the value of n = 1, then it represents a reversible __________ process. A. isothermal B. isobaric C. polytropic D. adiabatic

Answer 278

A. isothermal

Question 279

For the gaseous phase chemical reaction, C2H4(g) + H2O(g) ⇌ C2H5OH(g), the equilibrium conversion does not depend on the A. steam to ethylene ratio. B. temperature. C. pressure. D. none of these.

Answer 279

D. none of these.

Question 280

The first law of thermodynamics is a statement of conservation of A. heat B. momentum C. energy D. work

Answer 280

C. energy

Question 281

“Dry ice” is A. moisture free ice B. solid helium C. solid carbon dioxide D. none of these

Answer 281

C. solid carbon dioxide

Question 282

Which of the following non-flow reversible compression processes require maximum work ? A. Adiabatic process B. Isothermal process C. Isobaric process D. All require same work

Answer 282

A. Adiabatic process

Question 283

Pick out the correct statement. A. A real gas on expansion in vacuum gets heated up. B. An ideal gas on expansion in vacuum gets cooled. C. An ideal gas on expansion in vacuum gets heated up. D. A real gas on expansion in vacuum cools down whereas ideal gas remains unaffected.

Answer 283

D. A real gas on expansion in vacuum cools down whereas ideal gas remains unaffected.

Question 284

“When a system in equilibrium is subjected to a change in temperature, pressure or concentration, the equilibrium is displaced in a direction which tends to undo the effect of the change.” This is called the A. Le-Chatelier principle. B. Kopp’s rule. C. law of corresponding state. D. Arrehenius hypothesis.

Answer 284

A. Le-Chatelier principle.

Question 285

Sound waves propagation in air exemplifies an __________ process. A. adiabatic B. isothermal C. isometric D. none of these

Answer 285

A. adiabatic

Question 286

For equilibrium process (i.e. reversible) in an isolated system A. ds = 0 B. ds < 0 C. ds > 0 D. ds = Constant

Answer 286

A. ds = 0

Question 287

The partial molar enthalpy of a component in an ideal binary gas mixture of composition Z, at a temperature T and pressure P, is a function only of A. T B. T and P C. T, P and Z D. T and Z

Answer 287

B. T and P

Question 288

With increase in reduced temperature, the fugacity co-efficient of a gas at constant reduced pressure A. increases B. decreases C. remains same D. decreases linearly

Answer 288

A. increases

Question 289

For an ideal gas, the enthalpy A. increases with rise in pressure. B. decreases with rise in pressure. C. is independent of pressure. D. is a path function.

Answer 289

C. is independent of pressure.

Question 290

Efficiency of a heat engine working on Carnot cycle between two temperature levels depends upon the A. two temperatures only. B. pressure of working fluid. C. mass of the working fluid. D. mass and pressure both of the working fluid.

Answer 290

A. two temperatures only.

Question 291

In Joule-Thomson porous plug experiment, the A. enthalpy does not remain constant. B. entire apparatus is exposed to surroundings. C. temperature remains constant. D. none of these.

Answer 291

A. enthalpy does not remain constant.

Question 292

A Carnot cycle consists of the following steps : A. Two isothermals and two isentropics. B. Two isobarics and two isothermals. C. Two isochorics and two isobarics. D. Two isothermals and two isochorics.

Answer 292

A. Two isothermals and two isentropics.

Question 293

For a cyclic process, a fixed ratio between heat and work A. always exists B. may exist C. never exists D. is difficult to predict

Answer 293

A. always exists

Question 294

Which of the following is not a common refrigerant ? A. Freon-12 B. Ethylene C. Ammonia D. Carbon dioxide

Answer 294

B. Ethylene

Question 295

The most important application of distribution law is in A. evaporation B. liquid extraction C. drying D. distillation

Answer 295

B. liquid extraction

Question 296

Pick out the correct statement. A. Entropy and enthalpy are path functions. B. In a closed system, the energy can be exchanged with the surrounding, while. matter can not be exchanged. C. All the natural processes are reversible in nature. D. Work is a state function.

Answer 296

C. All the natural processes are reversible in nature.

Question 297

In vapour compression refrigeration system, if the evaporator temperature and the condenser temperatures are -13°C and 37°C respetively, the Carnot COP will be A. 5.2 B. 6.2 C. 0.168 D. data insufficient, can’t be found out

Answer 297

A. 5.2

Question 298

Gibbs free energy of mixing at constant pressure and temperature is always A. 0 B. ∞ C. + ve D. - ve

Answer 298

D. - ve

Question 299

The compressibility factor for an ideal gas is 1. Its value for any other real gas is A. 1 B. < 1 C. > 1 D. either (b) or (c), depends on the nature of the gas

Answer 299

D. either (b) or (c), depends on the nature of the gas

Question 300

If two gases have same reduced temperature and reduced pressure, then they will have the same A. volume B. mass C. critical temperature D. none of these

Answer 300

D. none of these

Question 301

Which of the following is an extensive property of a system ? A. Heat capacity B. Molal heat capacity C. Pressure D. Concentration

Answer 301

A. Heat capacity

Question 302

The reaction A (l) → R(g) is allowed to reach equilibrium conditions in an autoclave. At equilibrium, there are two phases, one a pure liquid phase of A and the other a vapor phase of A, R and S. Initially A alone is present. The number of degrees of freedom are A. 1 B. 2 C. 3 D. 0

Answer 302

A. 1

Question 303

Cp - Cv = R is valid for __________ gases. A. ideal B. all C. very high pressure D. very low temperature

Answer 303

A. ideal

Question 304

At a given temperature, the volume of a gas dissolved in a solvent __________ with increase in pressure. A. increases B. decreases C. remains unchanged D. may increase or decrease; depends on the gas

Answer 304

C. remains unchanged

Question 305

Which is an example of closed system ? A. Air compressor B. Lquid cooling system of an automobile C. Boiler D. None of these

Answer 305

B. Lquid cooling system of an automobile

Question 306

Melting of wax is accompanied with __________ in entropy. A. increase B. decrease C. no change D. none of these

Answer 306

A. increase

Question 307

A thermodynamic system is taken from state A to B along ACB and is brought back to A along BDA as shown below in the P-V diagram. (1) The net work done during the complete cycle is given by the area covered by A. P1ACBP2P1 B. ACBB1A1A C. ACBDA D. ADBB1A1A

Answer 307

C. ACBDA

Question 308

Work done in case of free expansion is A. indeterminate B. zero C. negative D. none of these

Answer 308

B. zero

Question 309

Chemical potential (an intensive property) of a substance is a force that drives the chemical system to equilibrium and is equal to its partial molar properties. The reatio of chemical potential to free energy of a pure substance at oconstant temperature and pressure is A. 0 B. 1 C. ∞ D. none of these

Answer 309

B. 1

Question 310

During adiabatic expansion of gas A. pressure remains constant. B. pressure is increased. C. temperature remains constant. D. none of these.

Answer 310

D. none of these.

Question 311

Which of the following has the minimum value of COP for a given refrigeration effect? A. Reverse Carnot cycle. B. Ordinary vapour-compression cycle. C. Vapour-compression process with a reversible expansion engine. D. Air refrigeration cycle.

Answer 311

D. Air refrigeration cycle.

Question 312

__________ decreases during adiabatic throttling of a perfect gas. A. Entropy B. Temperature C. Enthalpy D. Pressure

Answer 312

D. Pressure

Question 313

Pick out the wrong statement. A. Minimum number of degree of freedom of a system is zero. B. Degree of freedom of a system containing a gaseous mixture of helium, carbon dioxide and hydrogen is 4. C. For a two phase system in equilibrium made up of four non-reacting chemical species, the number of degrees of freedom is 4. D. Enthalpy and internal energy change is zero during phase change processes like melting, vaporisation and sublimation.

Answer 313

D. Enthalpy and internal energy change is zero during phase change processes like melting, vaporisation and sublimation.

Question 314

Tea kept in a thermos flask is vigorously shaken. If the tea is considered as a system, then its temperature will A. increase B. decrease C. remain unchanged D. first fall and then rise.

Answer 314

A. increase

Question 315

Change of heat content when one mole of compound is burnt in oxygen at constant pressure is called the A. calorific value B. heat of reaction C. heat of combustion D. heat of formation

Answer 315

C. heat of combustion

Question 316

Clausius - Clayperon equation is applicable to __________ equilibrium processes. A. solid-vapor B. solid-liquid C. liquid-vapor D. all of these

Answer 316

D. all of these

Question 317

In which of the following reaction equilibria, the value of equilibrium constant Kp will be more than is Kc ? A. 2HI ⇌ H2 + I2 B. N2O4 ⇌ 2NO2 C. 2SO2 + O2 ⇌ 2SO3 D. none of these

Answer 317

B. N2O4 ⇌ 2NO2

Question 318

After throttling, gas temperature A. decreases B. increases C. remains same D. may increase or decrease ; depends on the nature of the gas

Answer 318

A. decreases

Question 319

The chemical potential for a pure substance is __________ its partial molal free energy. A. more than B. less than C. equal to D. not related to

Answer 319

C. equal to

Question 320

When liquid and vapour phase of multi-component system are in equilibrium (at a given temperature and pressure), then chemical potential of each component is A. same in both the phases. B. zero in both the phases. C. more in vapour phase. D. more in liquid phase.

Answer 320

A. same in both the phases.

Question 321

COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about A. 0.5 B. 3.5 C. 4.5 D. 8.5

Answer 321

B. 3.5

Question 322

The number of degrees of freedom for a mixture of ice and water (liquid) are A. 2 B. 3 C. 1 D. 0

Answer 322

C. 1

Question 323

On opening the door of an operating refrigerator kept in a closed room, the temperature of the room will A. increase B. decrease C. remain same D. increase in summer and will decrease in winter

Answer 323

A. increase

Question 324

Domestic refrigerator usually works on the __________ refrigeration cycle. A. Carnot B. air C. absorption D. vapour-ejection

Answer 324

C. absorption

Question 325

Gibbs-Duhem equation A. states that n1dμ1 + n2dμ2 + ….njdμj = 0, for a system of definite composition at constant temperature and pressure. B. applies only to binary systems. C. finds no application in gas-liquid equilibria involved in distillation. D. none of these

Answer 325

A. states that n1dμ1 + n2dμ2 + ….njdμj = 0, for a system of definite composition at constant temperature and pressure.

Question 326

Minimum number of phases that exists in a system is 1. Number of chemical species in a colloidal system is A. 1 B. 4 C. 2 D. 3

Answer 326

C. 2

Question 327

The internal energy of a gas obeying P (V - b) RT (where, b is a positive constant and has a constant Cv), depends upon its A. pressure B. volume C. temperature D. all of these.

Answer 327

C. temperature

Question 328

“When a gas is expanded from high pressure region to low pressure region ; temper -ature change occurs”. This phenomenon is related to the A. Gibbs-Duhem equation B. Gibbs-Helmholtz equation C. Third law of thermodynamics D. Joule-Thomson effect

Answer 328

D. Joule-Thomson effect

Question 329

The internal energy of an ideal gas does not change in a reversible __________ process. A. isothermal B. adiabatic C. isobaric D. isometric

Answer 329

A. isothermal

Question 330

A/an __________ system is exemplified by a vessel containing a volatile liquid in contact with its vapor. A. isolated B. closed C. open D. none of these

Answer 330

C. open

Question 331

In a P-V diagram (for an ideal gas), an isothermal curve will coincide withan adiabatic curve (through a point), when A. Cp < Cv B. Cp = Cv C. Cp > Cv D. C ≥ Cv

Answer 331

B. Cp = Cv

Question 332

For an ideal gas, the chemical potential is given by A. RT dlnP B. R dlnP C. R dlnf D. none of these

Answer 332

A. RT dlnP

Question 333

Two substances are in equilibrium in a reversible chemical reaction. If the concentration of each substance is doubled, then the value of the equilibrium constant will be A. same B. doubled C. halved D. one fourth of its original value

Answer 333

A. same

Question 334

In the ammonia synthesis reaction, N2 + 3H2 ⇌ 2NH3 + 22.4 kcal, the formation of NH3 will be favoured by A. high temperature. B. low pressure. C. low temperature only. D. both low temperature and high pressure.

Answer 334

D. both low temperature and high pressure.

Question 335

Entropy change for an irreversible isolated system is A. ∞ B. 0 C. < 0 D. > 0

Answer 335

D. > 0

Question 336

Heat requirement for decomposition of a compound into its elements is __________ that is evolved during the formation of that compound from its elements. A. the same B. less than C. greater than D. different than

Answer 336

A. the same

Question 337

The unit of equilibrium constant of a chemical reaction is the same as that of A. molar concentration B. temperature C. internal energy D. none of these

Answer 337

D. none of these

Question 338

Which of the following equations is obtained on combining 1st and 2nd law of thermodynamics, for a system of constant mass? A. dE = Tds - PdV B. dQ = CvdT + PdV C. dQ = CpdT + Vdp D. Tds = dE - PdV

Answer 338

A. dE = Tds - PdV

Question 339

The Joule-Thomson co-efficient is defined as (∂T/∂P)H. Its value at the inversion point is A. ∞ B. 1 C. 0 D. -ve

Answer 339

C. 0

Question 340

Fugacity of a component in an ideal gas mixture is euqal to the partial pressure of that component in the mixture. The fugacity of each component in a stable homogeneous solution at contant pressure and temperature __________ as its mole fraction increases. A. decreases B. decreases exponentially C. increases D. remains constant

Answer 340

C. increases

Question 341

Entropy is a/an A. state function B. macroscopic property C. extensive property D. none of these

Answer 341

D. none of these

Question 342

At triple point (for one component system), vapour pressure of solid as compared to that of liquid will be A. more B. less C. same D. more or less ; depending on the system.

Answer 342

C. same

Question 343

4 kg moles of an ideal gas expands in vacuum spontaneously. The work done is A. 4 J B. ∞ C. 0 D. 8 J

Answer 343

C. 0

Question 344

Which of the following is not correct for a reversible adiabatic process ? A. TVγ-1 = constant B. p1-γ.TY = constant C. PVγ = constant D. none of these

Answer 344

D. none of these

Question 345

The efficiency of a Carnot heat engine operating between absolute temperatures T1 and T2 (when, T1 > T2) is given by (T1 - T2)/T1. The co-efficient of performance (C.O.P.) of a Carnot heat pump operating between T1 and T2 is given by A. T1/(T1-T2) B. T2/(T1-T2) C. T1/T2 D. T2/R1

Answer 345

A. T1/(T1-T2)

Question 346

Throttling (Joule-Thomson effect) process is a constant __________ process. A. enthalpy B. entropy C. pressure D. none of these

Answer 346

A. enthalpy

Question 347

Boiling of liquid is accompanied with increase in the A. vapor pressure. B. specific Gibbs free energy. C. specific entropy. D. all of these

Answer 347

A. vapor pressure.

Question 348

Change of state namely evaportation condensation, freezing and melting is an __________ process. A. isothermal B. adiabatic C. isobaric D. isochoric

Answer 348

A. isothermal

Question 349

Which of the following is not an equation of state? A. Bertholet equation B. Clausius Clayperon equation C. Beattie-Bridgeman equation D. None of these

Answer 349

B. Clausius Clayperon equation

Question 350

A gas shows deviation from ideal behaviour at A. low pressure and high temperature. B. low pressure and low temperature. C. low temperature and high pressure. D. high temperature and high pressure.

Answer 350

C. low temperature and high pressure.

Question 351

The difference between isothermal compressibility and adiabatic compressibility for an ideal gas is A. 0 B. +ve C. -ve D. ∞

Answer 351

B. +ve

Question 352

The expression for entropy change given by, ΔS = - nR ln (P2/P1), holds good for A. expansion of a real gas. B. reversible isothermal volume change. C. heating of an ideal gas. D. cooling of a real gas.

Answer 352

B. reversible isothermal volume change.

Question 353

With increase in temperature, the internal energy of a substance A. increases B. decreases C. remains unchanged D. may increase or decrease; depends on the substance

Answer 353

A. increases

Question 354

It is desired to bring about a certain change in the state of a system by performing work on the system under adiabatic conditions. A. The amount of work needed is path dependent. B. Work alone can not bring out such a change of state. C. The amount of work needed is independent of path. D. More information is needed to conclude anything about the path dependence or otherwise of the work needed.

Answer 354

A. The amount of work needed is path dependent.

Question 355

For a constant pressure reversible process, the enthalpy change (ΔH) of the system is A. Cv.dT B. Cp.dT C. integ Cv.dT D. integ Cp.dT

Answer 355

C. integ Cv.dT

Question 356

The work done in isothermal compression compared to that in adiabatic compression will be A. less B. more C. same D. more or less depending upon the extent of work done

Answer 356

B. more

Question 357

For organic compounds, group contribution method can be used for the estimation of A. critical properties. B. specific gravity. C. specific volume. D. thermal conductivity.

Answer 357

A. critical properties.

Question 358

Specific __________ does not change during phase change at constant temperature and pressure. A. entropy B. Gibbs energy C. internal energy D. enthalpy

Answer 358

B. Gibbs energy

Question 359

When liquid and vapour phases of one component system are in equilibrium (at a given temperature and pressure), the molar free energy is A. more in vapour phase. B. more in liquid phase. C. same in both the phases. D. replaced by chemical potential which is more in vapour phase.

Answer 359

C. same in both the phases.

Question 360

Heat evolved/absorbed during conversion of a substance from one allotropic form to another is termed as the heat of A. fusion B. vaporisation C. transition D. none of these

Answer 360

C. transition

Question 361

What happens in a reversible adiabatic compression ? A. Heating occurs B. Cooling occurs C. Pressure is constant D. Temperature is constant

Answer 361

A. Heating occurs

Question 362

Sublimation temperature of dry ice (solid CO2) is __________ °C. A. -273 B. 0 C. -78 D. 5

Answer 362

C. -78

Question 363

If atmospheric temperature and dew point are nearly equal, then the relative humidity is A. zero B. 0.5 C. almost 100% D. unpredictable

Answer 363

C. almost 100%

Question 364

Entropy change in case of reversible adiabatic process is A. minimum B. zero C. maximum D. indeterminate

Answer 364

B. zero

Question 365

In reactions involving solids and liquids (where change in volume is negligible), the heat of reaction at constant pressure as compared to that at constant volume is A. more B. less C. same D. unpredictable; depends on the particular reaction

Answer 365

C. same

Question 366

The efficiency of an Otto engine compared to that of a diesel engine, for the same compression ratio will be A. more B. less C. same D. data insufficient to predict

Answer 366

A. more

Question 367

Mollier chart is a __________ plot. A. pressure vs enthalpy B. pressure vs volume C. enthalpy vs entropy D. temperature vs entropy

Answer 367

C. enthalpy vs entropy

Question 368

Variation of equilibrium pressure with temperature for any two phases of a given substances is given by the __________ equation. A. Gibbs-Duhem B. Maxwell’s C. Clayperon D. none of these

Answer 368

C. Clayperon

Question 369

Pick out the undesirable property for a good refrigerant. A. high thermal conductivity B. low freezing point C. large latent heat of vaporisation D. high viscosity

Answer 369

D. high viscosity

Question 370

Isotherm on an enthalpy-concentration diagram, for an ideal solution will be a A. straight line B. sine curve C. parabola D. hyperbola

Answer 370

A. straight line

Question 371

The fusion of a crystalline solid at its melting point to form a liquid at the same temperature is accompanied by A. decrease in enthalpy corresponding to evolution of heat. B. decrease of entropy. C. increase in enthalpy corresponding to absorption of heat. D. no change in enthalpy.

Answer 371

C. increase in enthalpy corresponding to absorption of heat.

Question 372

Melting of ice is an example of an __________ process. A. adiabatic B. isothermal C. isometric D. none of these

Answer 372

B. isothermal

Question 373

A cylinder contains 640 gm of liquid oxygen. The volume occupied (in litres) by the oxygen, when it is released and brought to standard conditions (0°C, 760 mm Hg) will be __________ litres. A. 448 B. 224 C. 22.4 D. data insufficient; can’t be computed

Answer 373

A. 448

Question 374

Rotary lime kiln is an example of a/an __________ system. A. closed B. open C. isolated D. non-thermodynamic

Answer 374

B. open

Question 375

Heat of reaction is A. dependent on pressure only. B. dependent on temperature only. C. dependent on both pressure and temperature. D. independent of temperature changes.

Answer 375

C. dependent on both pressure and temperature.

Question 376

The expression, , is for the____of an ideal gas. A. compressibility B. work done under adiabatic contition C. work done under isothermal condition D. co-efficient of thermal expansion

Answer 376

C. work done under isothermal condition

Question 377

What happens in a reversible adiabatic expansion process ? A. Heating takes place. B. Cooling takes place. C. Pressure is constant. D. Temperature is constant.

Answer 377

B. Cooling takes place.

Question 378

Degree of freedom of a system consisting of a gaseous mixture of H2 and NH3 will be A. 0 B. 1 C. 2 D. 3

Answer 378

D. 3

Question 379

On a P-V diagram of an ideal gas, suppose a reversible adiabatic line intersects a reversible isothermal line at point A. Then at a point A, the slope of the reversible adiabatic line (∂P/∂V)s and the slope of the reversible isothermal line (∂P/∂V)T are related as (where, y = Cp/Cv) A. (∂P/∂V)S = (∂P/∂V)T B. (∂P/∂V)S = [(∂P/∂V)T]^Y C. (∂P/∂V)S = y(∂P/∂V)T D. (∂P/∂V)S = 1/y(∂P/∂V)T

Answer 379

C. (∂P/∂V)S = y(∂P/∂V)T

Question 380

Pick out the wrong statement. A. The net change in entropy in any reversible cycle is always zero. B. The entropy of the system as a whole in an irreversible process increases. C. The entropy of the universe tends to a maximum. D. The entropy of a substance does not remain constant during a reversible adiabatie change.

Answer 380

C. The entropy of the universe tends to a maximum.

Question 381

Fugacity co-efficient of a substance is the ratio of its fugacity to A. mole fraction B. activity C. pressure D. activity co-efficient

Answer 381

D. activity co-efficient

Question 382

Dryness fraction of wet steam is defined as the ratio of mass of vapour in the mixture to the mass of mixture __________ calorimeter is not used for measuring the dryness fraction of steam. A. Bomb B. Separating C. Bucket D. Throttling

Answer 382

A. Bomb

Question 383

As the time is passing, entropy of the universe A. is increasing B. is decreasing C. remains constant D. data insufficient, can’t be predicted

Answer 383

A. is increasing

Question 384

Which of the following processes can not be made reversible even under ideal condition of operation? A. Free expansion of a gas. B. Compression of air in a compressor. C. Expansion of steam in a turbine. D. all of these.

Answer 384

A. Free expansion of a gas.

Question 385

The relation connecting the fugacities of various components in a solution with one another and to composition at constant temperature and pressure is called the __________ equation. A. Gibbs-Duhem B. Van Laar C. Gibbs-Helmholtz D. Margules

Answer 385

A. Gibbs-Duhem

Question 386

Which of the following identities can be most easily used to verify steam table data for superheated steam. A. (∂T/∂V)S = (∂p/∂S)V B. (∂T/∂P)S = (∂V/∂S)P C. (∂P/∂T)V = (∂S/∂V)T D. (∂V/∂T)P = -(∂S/∂P)T

Answer 386

D. (∂V/∂T)P = -(∂S/∂P)T

Question 387

In the equation PVn = constant, if the value of n = y = Cp/Cv, then it represents a reversible __________ process. A. isothermal B. adiabatic C. isentropic D. polytropic

Answer 387

C. isentropic

Question 388

The ammonia synthesis reaction represented by N2 + 3H2 ⇌ 2NH3 ; ΔH = - 22.4 kcal, is A. endothermic B. exothermic C. isothermal D. adiabatic

Answer 388

B. exothermic

Question 389

With increase in temperature, the atomic heat capacities of all solid elements A. increases B. decreases C. remains unchanged D. decreases linearly

Answer 389

A. increases

Question 390

The temperature at the eutectic point of the system is the __________ temperature that can be attained in the system. A. lowest B. highest C. average D. none of these

Answer 390

A. lowest

Question 391

The effect of changing the evaporator temperature on COP as compared to that of changing the condenser temperature (in vapour compression refrigeration system) is A. less pronounced B. more pronounced C. equal D. data insufficient, can’t be predicted.

Answer 391

B. more pronounced

Question 392

Steam undergoes isentropic expansion in a turbine from 5000 kPa and 400°C (entropy = 6.65 kJ/kg K) to 150 kPa) (entropy of saturated liquid = 1.4336 kJ/kg . K, entropy of saturated vapour = 7.2234 kJ/kg. K) The exit condition of steam is A. superheated vapour. B. partially condensed vapour with quality of 0.9. C. saturated vapour. D. partially condensed vapour with quality of 0.1.

Answer 392

A. superheated vapour.

Question 393

An isentropic process is carried out at constant A. volume B. pressure C. temperature D. all of these

Answer 393

A. volume

Question 394

All gases except __________ shows a cooling effect during throttling process at atmospheric temperature and pressure. A. oxygen B. nitrogen C. air D. hydrogen

Answer 394

D. hydrogen

Question 395

High pressure steam is expanded adiabati-cally and reversibly through a well insulated turbine, which produces some shaft work. If the enthalpy change and entropy change across the turbine are represented by ΔH and ΔS respectively for this process: A. Δ H = 0 and ΔS = 0. B. Δ H ≠ 0 and ΔS = 0. C. Δ H ≠ 0 and ΔS ≠ 0. D. Δ H = 0 and ΔS ≠ 0.

Answer 395

B. Δ H ≠ 0 and ΔS = 0.

Question 396

The necessary condition for phase equilibrium in a multiphase system of N components is that the A. chemical potentials of a given component should be equal in all phases. B. chemical potentials of all components should be same in a particular phase. C. sum of the chemical potentials of any given component in all the phases should be the same. D. none of these.

Answer 396

A. chemical potentials of a given component should be equal in all phases.

Question 397

Compressibility factor-reduced pressure plot on reduced co-ordinates facilitates A. use of only one graph for all gases. B. covering of wide range. C. easier plotting. D. more accurate plotting.

Answer 397

A. use of only one graph for all gases.

Question 398

Which of the following is not an intensive property ? A. Molar heat capacity B. Internal energy C. Viscosity D. None of these

Answer 398

B. Internal energy

Question 399

Pick out the wrong statement. A. At constant pressure, solubility of a gas in a liquid diminishes with rise in temperature. B. Normally, the gases which are easily liquified, are more soluble in common solvents. C. The gases which are capable of forming ions in aqueous solution, are much more soluble in water than in other solvents. D. At constant pressure, solubility of a gas in a liquid increases with rise in temperature.

Answer 399

A. At constant pressure, solubility of a gas in a liquid diminishes with rise in temperature.

Question 400

Gibbs phase rule finds application, when heat transfer occurs by A. conduction B. convection C. radiation D. condensation

Answer 400

D. condensation

Question 401

Absorption/evolution of heat during conversion of a substance from one allotropic form to another is termed as the heat of A. sublimation B. fusion C. transition D. vaporisation

Answer 401

C. transition

Question 402

Ideal gas law is applicable at A. low T, low P B. high T, high P C. low T, high P D. high T, low P

Answer 402

D. high T, low P

Question 403

Reduced pressure of a gas is the ratio of its A. pressure to critical pressure. B. critical pressure to pressure. C. pressure to pseudocritical pressure. D. pseudocritical pressure to pressure.

Answer 403

A. pressure to critical pressure.

Question 404

For a reversible process involving only pressure-volume work A. (dF)T, p < 0 B. (dF)T, p > 0 C. (dF)T, p = 0 D. (dA)T, v < 0

Answer 404

C. (dF)T, p = 0

Question 405

Air enters an adiabatic compressor at 300K. The exit temperature for a compression ratio of 3, assuming air to be an ideal gas (Y = Cp/Cv = 7/5) and the process to be reversible, is A. 300(32/7) B. 300(33/5) C. 300(333/7) D. 300(35/7)

Answer 405

A. 300(32/7)

Question 406

Entropy change for an irreversible process taking system and surrounding together is A. 0 B. > 0 C. < 0 D. none of these

Answer 406

B. > 0

Question 407

In a homogeneous solution, the fugacity of a component depends upon the A. pressure B. composition C. temperature D. all of these

Answer 407

D. all of these

Question 408

For an incompressible fluid, the __________ is a function of both pressure as well as temperature. A. internal energy B. enthalpy C. entropy D. all of these

Answer 408

B. enthalpy

Question 409

An ideal monoatomic gas is taken round the cycle ABCDA as shown below in the P-V diagram (1) The work done during the cycle is A. PV B. 2PV C. PV/2 D. 0

Answer 409

A. PV

Question 410

One ton of refrigeration capacity is equivalent to the heat removal rate of A. 50 k cal/hr B. 200 BTU/hr C. 200 BTU/minute D. 200 BTU/day

Answer 410

C. 200 BTU/minute

Question 411

What is the degree of freedom for a system comprising liquid water equilibrium with its vapour ? A. 0 B. 1 C. 2 D. 3

Answer 411

B. 1

Question 412

Equilibrium constant of a reaction varies with the A. initial concentration of the reactant. B. pressure. C. temperature. D. none of these.

Answer 412

C. temperature.

Question 413

Third law of thermodynamics is concerned with the A. value of absolute entropy. B. energy transfer. C. direction of energy transfer. D. none of these.

Answer 413

A. value of absolute entropy.

Question 414

Claude’s liquefaction process employs the cooling of gases by A. expansion in an engine B. following a constant pressure cycle C. throttling D. none of these

Answer 414

A. expansion in an engine

Question 415

Gibbs free energy (F) is defined as A. F = E - TS B. F = H - TS C. F = H + TS D. F = E + TS

Answer 415

B. F = H - TS

Question 416

The expression for entropy change given by, ΔS = nR ln (V2/V1) + nCv ln (T2/T1) is valid for A. reversible isothermal volume change. B. heating of a substance. C. cooling of a substance. D. simultaneous heating and expansion of an ideal gas.

Answer 416

D. simultaneous heating and expansion of an ideal gas.

Question 417

The second law of thermodynamics states that A. the energy change of a system undergoing any reversible process is zero. B. it is not possible to transfer heat from a lower temperature to a higher temperature. C. the total energy of system and surrounding remains the same. D. none of the above.

Answer 417

D. none of the above.

Question 418

Internal energy of an ideal gas A. increases with increase in pressure. B. decreases with increase in temperature. C. is independent of temperature. D. none of these.

Answer 418

D. none of these.

Question 419

A refrigerator works on the principle of __________ law of thermodynamics. A. zeroth B. first C. second D. third

Answer 419

C. second

Question 420

Pick out the wrong statement. A. The conversion for a gas phase reaction increases with decrease in pressure, if there is an increase in volume accompanying the reaction. B. With increase in temperature, the equilibrium constant increases for an exothermic reaction. C. The equilibrium constant of a reaction depends upon temperature only. D. The conversion for a gas phase reaction increases with increase in pressure, if there is a decrease in volume accompanying the reaction.

Answer 420

B. With increase in temperature, the equilibrium constant increases for an exothermic reaction.

Question 421

Pick out the wrong statement. A. Enthalpies of all elements in their standard states are assumed to be zero. B. Combustion reactions are never en-dothermic in nature. C. Heat of reaction at constant volume is equal to the change in internal energy. D. Claussius-clayperon equation is not applicable to melting process.

Answer 421

D. Claussius-clayperon equation is not applicable to melting process.

Question 422

Which of the following is affected by the temperature ? A. Fugacity B. Activity co-efficient C. Free energy D. all of these

Answer 422

D. all of these

Question 423

The molar excess Gibbs free energy, g^E, for a binary liquid mixture at T and P is given by, (g^E/RT) = A . x1. x2, where A is a constant. The corresponding equation for ln y1, where y1 is the activity co-efficient of component 1, is A. A . X2^2 B. Ax1 C. Ax2 D. Ax1^2

Answer 423

A. A . X2^2

Question 424

The adiabatic throttling process of a perfect gas is one of constant enthalpy A. in which there is a temperature drop. B. which is exemplified by a non-steady flow expansion. C. which can be performed in a pipe with a constriction. D. in which there is an increase in temperature.

Answer 424

C. which can be performed in a pipe with a constriction.

Question 425

For spontaneous changes in an isolated system (S = entropy) A. ds = 0 B. ds <0 C. ds > 0 D. ds = Constant

Answer 425

C. ds > 0

Question 426

A gas performs the maximum work, when it expands A. non-uniformly B. adiabatically C. isobarically D. isothermally

Answer 426

C. isobarically

Question 427

There is a change in __________ during the phase transition. A. volume B. pressure C. temperature D. all a, b & c

Answer 427

A. volume

Question 428

Which of the following is Virial equation of state? A. (p + a/V^2)(V - b) = nRT B. PV = nRT C. PV = A + B/V + C/V^2 + D/V^3 + … D.

Answer 428

C. PV = A + B/V + C/V^2 + D/V^3 + …

Question 429

Pressure-enthalpy chart is useful in refrigeration. The change in internal energy of an ideal fluid used in ideal refrigeration cycle is A. positive B. negative C. zero D. infinity

Answer 429

C. zero

Question 430

First law of thermodynamics deals with the A. direction of energy transfer. B. reversible processes only. C. irreversible processes only. D. none of these.

Answer 430

A. direction of energy transfer.

Question 431

Henry’s law is closely obeyed by a gas, when its __________ is extremely high. A. pressure B. solubility C. temperature D. none of these

Answer 431

D. none of these

Question 432

A solute distributes itself between two non-miscible solvents in contact with each other in such a way that, at a constant temperature, the ratio of its concentrations in two layers is constant, irrespective of its total amount”. This is A. the distribution law. B. followed from Margule’s equation. C. a corollary of Henry’s law. D. none of these.

Answer 432

A. the distribution law.

Question 433

A solid is transformed into vapour without going to the liquid phase at A. triple point B. boiling point C. below triple point D. always

Answer 433

A. triple point

Question 434

A gas mixture of three components is brought in contact with a dispersion of an organic phase in water. The degree of freedom of the system are A. 4 B. 3 C. 5 D. 6

Answer 434

B. 3

Question 435

1m^3 of an ideal gas at 500 K and 1000 kPa expands reversibly to 5 times its initial volume in an insulated container. If the specific heat capacity (at constant pressure) of the gas is 21 J/mole . K, the final temperature will be A. 35 K B. 174 K C. 274 K D. 154 K

Answer 435

C. 274 K

Question 436

For a thermodynamic system containing ‘x’ chemical species, the maximum number of phases that can co-exist at equilibrium is A. x B. x + 1 C. x + 2 D. x + 3

Answer 436

C. x + 2

Question 437

A reasonably general expression for vapour-liquid phase equilibrium at low to moderate pressure is Φi yi P = Yi xi fi° where, Φ is a vapor fugacity component, Yi is the liquid activity co-efficient and fi° is the fugacity of the pure component i. the Ki value (Yi = Ki xi) is therefore, in general a function of A. temperature only. B. temperature and pressure only. C. temperature, pressure and liquid composition xi only. D. temperature, pressure, liquid composition xi and vapour composition yi.

Answer 437

C. temperature, pressure and liquid composition xi only.

Question 438

Standard temperature and pressure (S.T.P.) is A. 0°C and 750 mm Hg B. 15°C and 750 mm Hg C. 0°C and 1 kgf/cm^2 D. 15°C and 1 kgf/cm^2

Answer 438

A. 0°C and 750 mm Hg

Question 439

Normal temperature and pressure (N.T.P.) corresponds to A. 0°C and 760 mm Hg. B. 15°C and 760 mm Hg. C. 20°C and 760 mm Hg. D. 0°C and 1 kgf/cm^2.

Answer 439

C. 20°C and 760 mm Hg.

Question 440

The minimum number of phases that can exist in a system is A. 0 B. 1 C. 2 D. 3

Answer 440

B. 1

Question 441

Enthalpy changes over a constant pressure path are always zero for __________ gas. A. any B. a perfect C. an easily liquefiable D. a real

Answer 441

B. a perfect

Question 442

The fugacity of a gas in a mixture is equal to the product of its mole fraction and its fugacity in the pure state at the total pressure of the mixture”. This is A. the statement as per Gibbs-Helmholtz B. called Lewis-Randall rule C. Henry’s law D. none of these

Answer 442

B. called Lewis-Randall rule

Question 443

__________ does not change during phase transformation processes like sublimation, melting & vaporisation. A. Entropy B. Gibbs free energy C. Internal energy D. all of these

Answer 443

B. Gibbs free energy

Question 444

Which one is true for a throttling process ? A. A gas may have more than one inversion temperatures. B. The inversion temperature is different for different gases. C. The inversion temperature is same for all gases. D. The inversion temperature is the temperature at which Joule-Thomson co-efficient is infinity.

Answer 444

B. The inversion temperature is different for different gases.

Question 445

Choose the condition that must be specified in order to liquify CO2 (triple point for CO2 is - 57°C and 5.2 atm). A. Pressure must be kept below 5.2 atm. B. Temperature must be kept above - 57°C. C. Pressure must be kept below 5.2 atm. and temperature must be kept above 57°C. D. Pressure and temperature must be kept below 5.2 atm. and - 57°C respectively.

Answer 445

D. Pressure and temperature must be kept below 5.2 atm. and - 57°C respectively.

Question 446

One mole of nitrogen at 8 bar and 600 K is contained in a piston-cylinder arrangement. It is brought to 1 bar isothermally against a resisting pressure of 1 bar. The work done (in Joules) by the gas is A. 30554 B. 10373 C. 4988.4 D. 4364.9

Answer 446

B. 10373

Question 447

Lenz’s law results from the law of conservation of A. mass B. momentum C. energy D. none of these

Answer 447

C. energy

Question 448

In the equation, PVn = constant, if the value of n is in between 1 and y (i.e. Cp/Cv), then it represents a reversible __________ process. A. isometric B. polytropic C. isentropic D. isobaric

Answer 448

B. polytropic

Question 449

Throttling process is a/an __________ process. A. reversible and isothermal B. irreversible and constant enthalpy C. reversible and constant entropy D. reversible and constant enthalpy

Answer 449

B. irreversible and constant enthalpy

Question 450

The main feature of Carnot refrigeration cycle is that, it A. does not need the addition of external work for its functioning. B. transfers heat from high temperature to low temperature. C. accomplishes the reverse effect of the heat engine. D. none of these.

Answer 450

C. accomplishes the reverse effect of the heat engine.

Question 451

Charles’ law for gases states that A. V/2 = Constant B. V ∞ 1/T C. V ∞ 1/p D. PV/T = Constant

Answer 451

A. V/2 = Constant

Question 452

If heat contents of CH4, C2H4 and C3H8 are -17.9, 12.5 and -24.8 kcal/mole respectively, than ΔH for the reaction CH4(g) + C2H4(g) C3H8(g) will be __________ Kcal. A. -19.4 B. -30.2 C. 55.2 D. -55.2

Answer 452

A. -19.4

Question 453

Helmholtz free energy (A) is defined as A. A = H - TS B. A = E - TS C. A = H + TS D. none of these

Answer 453

B. A = E - TS

Question 454

As pressure approaches zero, the ratio of fugacity to pressure (f/P) for a gas approaches A. zero B. unity C. infinity D. an indeterminate value

Answer 454

B. unity

Question 455

For any system, what is the minimum number of degrees of freedom? A. 1 B. 0 C. 2 D. 3

Answer 455

B. 0

Question 456

At 60° C, vapour pressure of methanol and water are 84.562 kPa and 19.953 kPa respectively. An aqueous solution of methanol at 60° C exerts a pressure of 39.223 kPa; the liquid phase and vapour phase mole fractions of methanol are 0.1686 and 0.5714 respectively. Activity co-efficient of methanol is A. 1.572 B. 1.9398 C. 3.389 D. 4.238

Answer 456

A. 1.572

Question 457

The variation of heat of reaction with temperature at constant pressure is given by the __________ law. A. Kelvin’s B. Antonie’s C. Kirchoffs D. none of these

Answer 457

C. Kirchoffs

Question 458

At absolute zero temperature, the __________ of the gas is zero. A. pressure B. volume C. mass D. none of these

Answer 458

B. volume

Question 459

Which of the following equations is used for the prediction of activity co-efficient from experiments ? A. Van Laar equation B. Margules equation C. Wilson’s equation D. all of these

Answer 459

D. all of these

Question 460

The equation, , applicable to a binary solution of components. A and B in equilibrium with their vapors at constant temperature and pressure is called the __________ equation. A. Van Laar B. Margules C. Gibbs-Duhem D. Gibbs-Duhem-Margules

Answer 460

D. Gibbs-Duhem-Margules

Question 461

Entropy of a substance remains constant during a/an __________ change. A. reversible isothermal B. irreversible isothermal C. reversible adiabatic D. none of these

Answer 461

C. reversible adiabatic

Question 462

Gases are cooled in Joule-Thomson expansion, when it is __________ inversion temperature. A. below B. at C. above D. either ‘b’ or ‘c’

Answer 462

A. below

Question 463

PVy = constant, holds good for an isentropic process, which is A. reversible and isothermal. B. isothermal and irreversible. C. reversible and adiabatic. D. adiabatic and irreversible.

Answer 463

C. reversible and adiabatic.

Question 464

Which of the following behaves most closely like an ideal gas ? A. He B. N2 C. O2 D. H2

Answer 464

A. He

Question 465

In the reaction, C + O2 → CO2 ; ΔH = - 94 kcal. What is the heat content (enthalpy)of O2? A. -94 kcal B. > -94 kcal C. < - 94 kcal D. zero

Answer 465

D. zero

Question 466

When a system is in equilibrium for all possible processes, the differential or finite change of entropy is A. < 0 B. > 0 C. 0 D. none of these

Answer 466

A. < 0

Question 467

A system is said to be at equilibrium, if the entropy of the system has reached __________ value. A. minimum B. zero C. maximum D. none of these

Answer 467

C. maximum

Question 468

In the equation, PV^n = constant, if the value of n = ± ∞, then it represents a reversible __________ process. A. adiabatic B. isometric C. isentropic D. isothermal

Answer 468

B. isometric

Question 469

Degree of freedom of the system ice-water-vapour will be A. 0 B. 1 C. 2 D. 3

Answer 469

A. 0

Question 470

A system in which there is exchange of energy but not of mass, is called a/an __________ system. A. isolated B. open C. insulated D. closed

Answer 470

D. closed

Question 471

The point at which all the three (solid, liquid and gas) phases co-exist, is known as the __________ point. A. freezing B. triple C. boiling D. Boyle

Answer 471

B. triple

Question 472

In an ideal gas mixture, fugacity of a species is equal to its A. vapor pressure B. partial pressure C. chemical potential D. none of these

Answer 472

B. partial pressure

Question 473

The third law of thermodynamics states that the A. heat capacity of a crystalline solid is zero at absolute zero temperature. B. heat transfer from low temperature to high temperature source is not possible without external work. C. gases having same reduced properties behave similarly. D. none of these.

Answer 473

A. heat capacity of a crystalline solid is zero at absolute zero temperature.

Question 474

Consider the reaction, C + O2 ⇌ CO2 ;ΔH = - 94 kcal. What will be the value of ΔH for the reaction CO2 C + O2 ? A. -94 kcal B. + 94 kcal C. > 94 kcal D. < -94 kcal

Answer 474

B. + 94 kcal

Question 475

Which is not a state function ? A. Specific volume B. Work C. Pressure D. Temperature

Answer 475

B. Work

Question 476

For an ideal liquid solution, which of the following is unity ? A. Activity B. Fugacity C. Activity co-efficient D. Fugacity co-efficient

Answer 476

C. Activity co-efficient

Question 477

In the decomposition of PCl5 represented by, PCl5 ⇌ PCl3 + Cl2, decrease in the pressure of the system will __________ the degree of dissociation of PCl5. A. increase B. decrease C. not alter D. none of these

Answer 477

A. increase

Question 478

To obtain integrated form of Clausius-Clayperon equation,(1), from the exact Clayperon equafion, it is assumed that the A. volume of the liquid phase is negligible compared to that of vapour phase. B. vapour phase behaves as an ideal gas. C. heat of vaporisation is independent of temperature. D. all of these.

Answer 478

D. all of these.

Question 479

In case of an __________ process, the temperature of the system increases. A. isothermal compression B. isothermal expansion C. adiabatic expansion D. adiabatic compression

Answer 479

D. adiabatic compression

Question 480

Cp of a gas at its critical temperature and pressure A. becomes zero. B. becomes infinity. C. equals 1 kcal/kmol °K. D. equals 0.24 kcal/kmol °K.

Answer 480

C. equals 1 kcal/kmol °K.

Question 481

Trouton’s ratio is given by (where λb, = molal heat of vaporisation of a substance at its normal boiling point, kcal/kmol Tb = normal boiling point, °K ) A. λb/Tb B. Tb/λb C. D.

Answer 481

A. λb/Tb

Question 482

Which of the following is true for Virial equation of state ? A. Virial co-efficients are universal constants. B. Virial co-efficients ‘B’ represents three body interactions. C. Virial co-efficients are function of temperature only. D. For some gases, Virial equations and ideal gas equations are the same.

Answer 482

C. Virial co-efficients are function of temperature only.

Question 483

Molar heat capacity of water in equilibrium with ice at constant pressure is __________ Kcal/kg mole . °K A. 0 B. ∞ C. 50 D. 100

Answer 483

B. ∞

Question 484

A gas can be liquified by pressure alone only, when its temperature is __________ its critical temperature. A. less than B. more than C. equal to or higher than D. less than or equal to

Answer 484

D. less than or equal to

Question 485

For an ideal gas, the internal energy depends upon its __________ only. A. molecular size B. temperature C. volume D. pressure

Answer 485

B. temperature

Question 486

Compound having large heat of formation is A. more stable. B. less stable. C. not at all stable (like nascent O2). D. either more or less stable ; depends on the compound.

Answer 486

A. more stable.

Question 487

Second law of thermodynamics is concerned with the A. amount of energy transferred. B. direction of energy transfer. C. irreversible processes only. D. non-cyclic processes only.

Answer 487

B. direction of energy transfer.