Chemical Engineering Thermodynamics Flashcards
Maximum work that could be secured by expanding the gas over a given pressure range is the __________ work.
- isothermal
- adiabatic
- isentropic
- none of these
isothermal
Internal energy change of a system over one complete cycle in a cyclic process is
- zero
- +ve
- -ve
- dependent on the path
zero
Heating of water under atmospheric pressure is an __________ process.
- isochoric
- isobaric
- adiabatic
- isothermal
isobaric
Van Laar equation deals with the activity co-efficients in
- binary solutions
- ternary solutions
- azeotropic mixture only
- none of these
binary solutions
High ________ is an undesirable property for a good refrigerant.
- specific heat
- latent heat of vaporisation
- viscosity
- specific vapor volume
viscosity
Solubility of a substance which dissolves with an increase in volume and liberation of heat will be favoured by the
- low pressure and high temperature.
- low pressure and low temperature.
- high pressure and low temperature.
- high pressure and high temperature.
low pressure and low temperature.
Entropy is a measure of the __________ of a system.
- disorder
- orderly behaviour
- temperature changes only
- none of these
disorder
A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is
- zero
- positive
- negative
- none of these
negative
Fundamental principle of refrigeration is based on the __________ law of thermodynamics.
- zeroth
- first
- second
- third
second
For a spontaneous process, free energy
- is zero
- increases
- decreases whereas the entropy increases
- and entropy both decrease
decreases whereas the entropy increases
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 ?
- Vapor compression cycle using expansion valve.
- Air refrigeration cycle.
- Vapor compression cycle using expansion engine.
- Carnot refrigeration cycle.
Carnot refrigeration cycle.
In a working refrigerator, the value of COP is always
- 0
- < 0
- < 1
- > 1
> 1
A refrigerator may be termed as a
- heat pump
- heat engine
- Carnot engine
- none of these
heat pump
For a stable phase at constant pressure and temperature, the fugacity of each component in a binary system ________ as its mole fraction increases.
- decreases
- increases
- remains same
- decreases linearly
increases
Which of the following is not an intensive property ?
- Chemical potential
- Surface tension
- Heat capacity
- None of these
Heat capacity
Out of the following refrigration cycles, which one has the minimum COP (Co-efficient of performance)?
- Air cycle
- Carnot cycle
- Ordinary vapour compression cycle
- Vapour compression with a reversible expansion engine
Air cycle
Measurement of thermodynamic property of temperature is facilitated by __________ law of thermodynamics.
- 1st
- zeroth
- 3rd
- none of these
zeroth
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
- -2 RT ln 0.5
- -RT ln 0.5
- 0.5 RT
- 2 RT
-RT ln 0.5
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.
- 270
- 327
- 300
- 540
327
Isobaric process means a constant process.
- temperature
- pressure
- volume
- entropy
pressure
No work is done by the system, when a reaction occurs at constant
- volume
- temperature
- pressure
- none of these
volume
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
- Maxwell’s equation
- Clayperon-Claussius equation
- Van Laar equation
- Nernst Heat Theorem
Clayperon-Claussius equation
The freezing point of a liquid decreases when the pressure is increased, if the liquid ________ while freezing.
- contracts
- expands
- does not change in volume
- either (a), (b) or (c)
contracts
“At the absolute zero temperature, the entropy of every perfectly crystalline substance becomes zero”. This follows from the
- third law of thermodynamics
- second law of thermodynamics
- Nernst heat theorem
- Maxwell’s relations
third law of thermodynamics
During Joule-Thomson expansion of gases
- enthalpy remains constant.
- entropy remains constant.
- temperature remains constant.
- none of these.
enthalpy remains constant.
The accentric factor of a materical, ‘ω’, is defined as ω = -log10(Prsat)Tr-1 = 0.7, where, Prsat = reduced vapor pressure, Tr = reduced temperature. The value of accentric factor is always
- > 2
- < 1
- > 1
- < 3
< 1
Degress of freedom at triple point will be
- 0
- 1
- 2
- 3
0
“Law of corresponding states” says that
- two different gases behave similarly, if their reduced properties (i.e. P, V and T) are same.
- the surface of separation (i. e. the meniscus) between liquid and vapour phase disappears at the critical temperature.
- no gas can be liquified above the critical temperature, howsoever high the pressure may be.
- the molar heat of energy of gas at constant volume should be nearly constant (about 3 calories).
two different gases behave similarly, if their reduced properties (i.e. P, V and T) are same.
Linde gas liquefaction process employs cooling
- by throttling
- by expansion in an engine
- at constant pressure
- none of these
by throttling
Pick out the wrong statement pertaining to the decomposition of PCl₅ represented by, PCl₅ → PCl₃ + Cl₂. Degree of dissociation of PCl₅ will
- decrease on addition of Cl₂.
- increase on addition of an inert gas at constant pressure.
- decrease on increasing the pressure of the system.
- none of these
none of these
Boyle’s law for gases states that
- P ∝ 1/V, when temperature is constant.
- P ∝ 1/V, when temperature & mass of the gas remain constant.
- P ∝ V, at constant temperature & mass of the gas.
- P/V= constant, for any gas.
P ∝ 1/V, when temperature & mass of the gas remain constant.
1st law of thermodynamics is nothing but the law of conservation of
- momentum
- mass
- energy
- none of these
energy
In a reversible chemical reaction (where, Δx = number of moles of products-number of moles of reactants )
- addition of inert gas favours the forward reaction, when Δx is positive.
- pressure has no effect on equilibrium, when Δn = 0.
- addition of inert gas has no effect on the equilibrium constant at constant volume for any value of Δx (+ ve, - ve) or zero).
- all ‘a’, ‘b’ & ‘c’.
all ‘a’, ‘b’ & ‘c’.
Out of the following refrigeration cycles, which one has maximum COP ?
- Air cycle
- Carnot cycle
- Ordinary vapor compression cycle
- Vapor compression with a reversible expansion engine
Carnot cycle
Pick out the correct statement:
- In an isothermal system, irreversible work is more than reversible work.
- Under reversible conditions, the adiabatic work is less than isothermal work.
- Heat, work, enthalpy and entropy are all ‘state functions’.
- Matter and energy can not be exchanged with the surroundings in a closed system.
Under reversible conditions, the adiabatic work is less than isothermal work.
In any spontaneous process,
- only F decreases
- only A decreases
- both F and A decreases
- both F and A increase
both F and A decreases
Which of the following is a thermodynamic property of a system ?
- Concentration
- Mass
- Temperature
- Entropy
Entropy
Equilibrium constant decreases as the temperature
- increases, for an exothermic reaction.
- decreases, for an exothermic reaction.
- increases, for an endothermic reaction.
- none of these.
increases, for an exothermic reaction.
The expression, ΔG = nRT · ln (P2/P1) , gives the free energy change
- with pressure changes at constant temperature.
- under reversible isothermal volume change.
- during heating of an ideal gas.
- during cooling of an ideal gas.
with pressure changes at constant temperature.
All gases during throttling process at atmospheric temperature and pressure show a cooling effect except
- CO₂
- H₂
- O₂
- N₂
H₂
Compressibility factor for almost all the gases are approximately same at the same
- pressure and temperature.
- reduced pressure and reduced temperature.
- critical pressure and critical temperature.
- none of these.
reduced pressure and reduced temperature.
Pick out the wrong statement.
- Activity co-efficient is dimensionless.
- In case of an ideal gas, the fagacity is equal to its pressure.
- In a mixture of ideal gases, the fugacity of a component is equal to the partial pressure of the component.
- The fugacity co-efficient is zero for an ideal gas.
The fugacity co-efficient is zero for an ideal gas.
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.
- kinematic viscosity
- work
- temperature
- none of these
none of these
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
- (∂E/∂nᵢ) s,v,ni
- (∂G/∂nᵢ) T,P,nj = (∂A/∂nᵢ) T,v,nj
- ∂G/∂nᵢ)S,P,nj
- all (a), (b) and (c)
all (a), (b) and (c)
In jet refrigerators, the refrigerating fluid is practically always
- water
- ammonia
- freon
- brine
water
Water on heating from 1 to 4°C
- contracts
- expands
- has same volume
- may contract or expand
contracts
Pick out the correct statement.
- Compression ratio of an Otto engine is comparatively higher than a diesel engine.
- Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio.
- Otto engine efficiency decreases with the rise in compression ratio, due to decrease in work produced per quantity of heat.
- Diesel engine normally operates at lower compression ratio than an Otto engine for an equal output of work.
Efficiency of an Otto engine is higher than that of a diesel engine for the same compression ratio.
When pressure is applied on the system, icewater, then
- equilibrium can not be established.
- more ice will be formed.
- more water will be formed.
- evaporation of water will take place.
more water will be formed.
Partial molar free energy of an element A in solution is same as its
- chemical potential
- activity
- fugacity
- activity co-efficient
chemical potential
Free energy change at equilibrium is
- zero
- positive
- negative
- indeterminate
zero
The temperature at which both liquid and gas phases are identical, is called the __________ point.
- critical
- triple
- freezing
- boiling
critical
What is the value of ln y (where y = activity co-efficient) for ideal gases ?
- Zero
- Unity
- Infinity
- Negative
Zero
A closed system is cooled reversibly from 100°C to 50°C. If no work is done on the system
- its internal energy (U) decreases and its entropy (S) increases.
- U and S both decreases
- U decreases but S is constant.
- U is constant but S decreases.
U and S both decreases
Which is not a refrigerant ?
- SO₂
- NH₃
- CCl₂F₂
- C₂H₄Cl₂
C₂H₄Cl₂
The partial pressure of each constituent present in an alloy is ________ the total vapor pressure exerted by the alloy.
- less than
- equal to
- more than
- either (b) or (c); depends on the type of alloy
less than
The four properties of a system viz. P, V, T, S are related by __________ equation.
- Gibbs-Duhem
- Gibbs-Helmholtz
- Maxwell’s
- none of these
Maxwell’s
If the pressure on 100 c.c. of air is halved, then its volume (at the same temperature) would be __________ c.c.
- 100
- 50
- 205
- 200
200
Pick out the wrong statement.
- Cp of monoatomic gases such as metallic vapor is about 5 kcal/kg.atom.
- The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state.
- There is an increase in entropy, when a spontaneous change occurs in an isolated system.
- At absolute zero temperature, the heat capacity for many pure crystalline substances is zero.
The heat capacity of solid inorganic substance is exactly equal to the heat capacity of the substance in the molten state.
Co-efficient of performance for a reversed Carnot cycle working between temperatures T1 and T2 (T1 > T2) is
- T₂ / T₁-T₂
- T₁ / T₁-T₂
- T₁-T₂ / T₁
- T₁-T₂ / T₂
T₂ / T₁-T₂
The number of degrees of freedom for an azeotropic mixture in a two component vapour-liquid equilibria is/are
- zero
- one
- two
- three
one
Any substance above its critical temperature exists as
- saturated vapour
- solid
- gas
- liquid
gas
Which of the following decreases with increase in pressure ?
- Melting point of ice
- Melting point of wax
- Boiling point of liquids
- none of these
Melting point of ice
Isentropic process means a constant __________ process.
- enthalpy
- pressure
- entropy
- none of these
entropy
(1/V)(∂V/∂V)ₚ is the mathematical expression
- Joule-Thomson co-efficient.
- specific heat at constant pressure (Cp).
- co-efficient of thermal expansion.
- specific heat at constant volume (CV).
co-efficient of thermal expansion.
In case of steady flow compression polytropic process (PVn = constant), the work done on air is the lowest, when
- n = y = 1.4
- n = 0
- n = 1
- n = 1.66
n = 1
liquid under pressure greater than its vapour pressure for the temperature involved is called a __________ liquid.
- subcooled
- saturated
- non-solidifiable
- none of these
subcooled
For a real gas, the chemical potential is given by
RT dlnP
RT dlnf
R dlnf
none of these
RT dlnf
At absolute zero temperature, all substances have the same
- heat capacity
- crystalline structure
- entropy
- none of these
heat capacity
Lowering of condenser temperature (keeping the evaporator temperature constant) in case of vapour compression refrigeration system results in
- increased COP.
- same COP.
- decreased COP.
- increased or decreased COP ; depending upon the type of refrigerant.
increased COP.
Pick out the correct statement.
- If an insoluble gas is passed through a volatile liquid placed in a perfectly insulated container, the temperature of the liquid will increase.
- A process is irreversible as long as Δ S for the system is greater than zero.
- The mechanical work done by a system is always equal to ∫P.dV.
- The heat of formation of a compound is defined as the heat of reaction leading to the formation of the compound from its reactants.
The heat of formation of a compound is defined as the heat of reaction leading to the formation of the compound from its reactants.
Grams of butane (C₄H₁₀) formed by the liquefaction of 448 litres of the gas (measured at (STP) would be
- 580
- 640
- 1160
- data insufficient; can’t be computed
1160
The thermodynamic law, PVʸ = constant, is
not applicable in case of
- ideal compression of air.
- free expansion of an ideal gas.
- adiabatic expansion of steam in a turbine.
- adiabatic compression of a perfect gas.
free expansion of an ideal gas.
What is the value of maximum COP in case of absorption refrigeration, if refrigeration provided is at temperature, TR (where, T1 and T2 are source & surrounding temperatures respectively.)?
Mollier diagram is a plot of
- temperature vs. enthalpy
- temperature vs. enthalpy
- entropy vs. enthalpy
- temperature vs. internal energy
entropy vs. enthalpy
(∂H/∂T)P is the mathematical expression for
- Cᵥ
- enthalpy change
- free energy change
- none of these
none of these
The activity of an ideal gas is numerically __________ its pressure.
- more than
- less than
- equal to
- data insufficient, can’t be predicted
equal to
Which of the following diagrams does not represent an Otto cycle ?
Specific heat of a gas for a reversible adiabatic process is
- negative
- zero
- infinity
- none of these
zero
When a gas in a vessel expands, its internal energy decreases. The process involved is
- reversible
- irreversible
- isothermal
- adiabatic
reversible
true ans: adiabatic
A system is said to be isopiestic, if there is no __________ change.
- temperature
- pressure
- volume
- none of these
pressure
In a turbine, the fluid expands almost
- isothermally
- isobarically
- adiabatically
- none of these
adiabatically
The unity of Planck’s constant ‘h’ in the equation, E = hv is
- J/s
- J.S
- J/kmol
- kmol/J
J.S
Specific/molar Gibbs free energy for a pure substance does not change during
- sublimation
- vaporisation
- melting
- either (a), (b) or (c)
either (a), (b) or (c)
Refrigeration capacity of a household refrigerator may be round about __________ tons.
- 0.15
- 1.5
- 4.5
- 6.5
0.15
(∂H/∂T)ₚ is the mathematical expression for
- CV
- entropy change
- Gibbs free energy
- none of these
none of these
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
- 12 P1V1
- 6 P1 V1
- 3 P1V1
- P1 V1
3 P1V1
In polytropic process (PVⁿ = constant), if n = 1; it means a/an __________ process.
- adiabatic
- reversible
- isothermal
- none of these
isothermal
The melting point of paraffin wax (which contracts on solidification) __________ with pressure rise.
- increases
- decreases
- remains unchanged
- decreases linearly
increases
Co-efficient of Performance (COP) of a refrigerator is the ratio of the
- work required to refrigeration obtained.
- refrigeration obtained to the work required.
- lower to higher temperature.
- higher to lower temperature.
refrigeration obtained to the work required.
The Maxwell relation derived from the differential expression for the Helmholtz free energy (dA) is
dW and dq are not the exact differential, because q and W are
- state functions
- path functions
- intensive properties
- extensive properties
path functions
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
- -1.87
- 0
- 1.26
- 3.91
0
Trouton’s ratio of __________ liquids is calculated using Kistyakowsky equation.
- polar
- non-polar
- both (a) & (b)
- neither (a) nor (b)
non-polar
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
- infinity
- unity
- constant
- negative
constant
Activity co-efficient is a measure of the
- departure from ideal solution behaviour.
- departure of gas phase from ideal gas law.
- vapour pressure of liquid.
- none of these.
departure from ideal solution behaviour.
Which of the following units is not present in both the vapor compression refrigeration system and absorption refrigeration system ?
- Expansion valve
- Condenser
- Refrigerator
- Compressor
Compressor
For an isothermal reversible compression of an ideal gas
- only ΔE = 0
- only ΔH =0
- ΔE = ΔH = 0
- dQ = dE
ΔE = ΔH = 0
Melting of ice exemplifies a/an
- adiabatic process.
- endothermic reaction.
- exothermic reaction.
- process involving a chemical reaction.
endothermic reaction.
A refrigeration cycle is the same as a __________ cycle,
- turbine
- heat engine
- reversed heat engine
- none of these
reversed heat engine
At ________ point, all the three phases (i.e.solid, liquid and gas) co-exist.
- eutcetic
- triple
- plait
- critical
triple
Kopp’s rule is used to calculate the heat capacity of
- solids
- liquids
- gases
- all (a), (b) & (c)
solids
________ explains the equilibrium constant for any chemical reaction.
- Henry’s law
- Law of mass action
- Hess’s law
- none of these
Law of mass action
Which of the following is not a reversible process ?
- Expansion of an ideal gas against constant pressure.
- Atmospheric pressure vaporisation of water at 100°C.
- Solution of NaCl in water at 50°C.
- None of these.
Solution of NaCl in water at 50°C.
Pick out the wrong statement.
- A closed system does not permit exchange of mass with its surroundings but may permit exchange of energy.
- An open system permits exchange of both mass and energy with its surroundings.
- The term microstate is used to characterise an individual, whereas macro-state is used to designate a group of micro-states with common characteristics.
- none of the above.
none of the above.
Which of the following exemplifies an adiabatic process ?
- Melting of ice.
- Condensation of alcohol vapor.
- Sudden bursting of a cycle tube.
- Evaporation of water.
Sudden bursting of a cycle tube.
Entropy, which is a measure of the disorder of a system is
- independent of pressure.
- independent of temperature.
- zero at absolute zero temperature for a perfect crystalline substance.
- all (a), (b) & (c)
zero at absolute zero temperature for a perfect crystalline substance.
Critical temperature is defined as the temperature above which a gas will
- not liquify (barring exceptions).
- immediately liquify.
- never liquify however high the pressure may be.
- none of these.
never liquify however high the pressure may be.
The **standard Gibbs free energy **change of a reaction depends on the equilibrium
- pressure
- temperature
- composition
- all (a), (b) and (c)
temperature
Gibbs-Duhem equation relates composition in liquid phase and the __________ at constant temperature & pressure.
- fugacity
- partial pressure
- activity co-efficient
- (a), (b), and (c)
(a), (b), and (c)
In an ideal solution, the activity of a component equals its
- mole fraction.
- fugacity at the same temperature and pressure.
- partial pressure.
- none of these.
mole fraction.
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.
- 2.73
- 28.3
- 273
- 283
28.3
Clayperon equation deals with the
- rate of change of vapour pressure with temperature.
- effect of an inert gas on vapour pressure.
- calculation of ΔF for spontaneous phase change.
- temperature dependence of heat of phase transition.
rate of change of vapour pressure with temperature.
Which of the following is an undesirable characteristics of a refrigerant ?
- It should be non-explosive.
- It should have a sub-atmospheric vapor pressure at the temperature in refrigerator coils.
- Its vapor pressure at the condenser temperature should be very high.
- None of these.
It should have a sub-atmospheric vapor pressure at the temperature in refrigerator coils.
“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
- Lewis-Randall rule.
- statement of Vant-Hoff equation.
- Le-Chatelier’s principle.
- none of these.
none of these.
What is the ratio of adiabatic compressibility to isothermal compressibility ?
- 1
- < 1
- > 1
- > > 1
< 1
The absolute entropy for all crystalline substances at absolute zero temperature is
- zero
- negative
- more than zero
- indeterminate
zero
Pick out the wrong statement.
- Phase rule variables are intensive properties.
- Heat and work are both state function.
- The work done by expansion of a gas in vacuum is zero.
- CP and CV are state function.
Heat and work are both state function.
Compressibility factor of a gas is
- not a function of its pressure.
- not a function of its nature.
- not a function of its temperature.
- unity, if it follows PV = nRT.
unity, if it follows PV = nRT.
Which of the following is not an extensive property ?
- Free energy
- Entropy
- Refractive index
- None of these
Refractive index
Forward reaction will be favoured for the exothermic reaction, represented by CO + H2O ⇌ CO2 + H2, by
- low temperature and high pressure.
- low temperature and low pressure.
- high temperature and high pressure.
- high temperature and low pressure.
low temperature and high pressure.
Enthalpy of a gas depends upon its
- temperature
- mass
- volume
- pressure
temperature
When dilute aqueous solutions of two salts are mixed, the process is associated with
- decrease in temperature.
- increase in temperature.
- no change in temperature.
- change in temperature which is a function of composition.
increase in temperature.
Pick out the correct statement.
- Like internal energy and enthalphy, the absolute value of standard entropy for elementary substances is zero.
- Melting of ice involves increase in enthalpy and a decrease in randomness.
- The internal energy of an ideal gas depends only on its pressure.
- Maximum work is done under reversible conditions.
Maximum work is done under reversible conditions.
Chemical engineering thermodynamics is concerned with the __________ in/of chemical processes.
- reaction mechanism
- calculation of rates
- energy transformation from one form to the another
- none of these
energy transformation from one form to the another
An isolated system can exchange __________ with its surroundings.
- matter
- energy
- neither matter nor energy
- both matter and energy
neither matter nor energy
Requisites of a reversible process is that the
- system and surroundings pressure be equal.
- friction in the system should be absent.
- system and surroundings temperature be equal.
- none of these.
friction in the system should be absent.
Fugacity is most helpful in
- representing actual behaviour of real gases.
- representing actual behaviour of ideal gases.
- the study of chemical equilibria involving gases at atmospheric pressure.
- none of these
representing actual behaviour of real gases.
The energy of activation of exothermic reaction is
- zero.
- negative.
- very large compared to that for endothermic reaction.
- not possible to predict.
not possible to predict.
Pick out the wrong statement.
- The chemical potential of a pure substance depends upon the temperature and pressure.
- The chemical potential of a component in a system is directly proportional to the escaping tendency of that component.
- 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.
- The chemical potential of species ‘i’ in the mixture (μi) is mathematically represented as, μi = [∂(nG)/∂ni]T,P,nj 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.
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.
In the reaction; N2 + O2 ⇌ 2NO, increasing the pressure will result in
- shifting the equilibrium towards right,
- shifting the equilibrium towards left.
- no change in equilibrium condition.
- none of these.
no change in equilibrium condition.
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
- 349
- 651
- 667
- 1000
349
Pick out the wrong statement.
- Trouton’s ratio of non-polar liquids is calculated using Kistyakowasky equation.
- Thermal efficiency of a Carnot engine is always less than 1.
- An equation relating pressure, volume and temperature of a gas is called ideal gas equation.
- none of these.
An equation relating pressure, volume and temperature of a gas is called ideal gas equation.
Which of the following is clausius-Clayperon equation for vaporisation of an ideal gas under the condition that the molar volume of liquid is negligible compared to that of the vapor ?
- dlnp / dt = Hvap / RT²
- dlnp / dt = RT² / Hvap
- dp/dt = RT² / Hvap
- dp/dt = Hvap / RT²
dlnp / dt = Hvap / RT²
When a gas is subjected to adiabatic expansion, it gets cooled due to
- decrease in velocity.
- decrease in temperature.
- decrease in kinetic energy.
- energy spent in doing work.
energy spent in doing work.
Joule-Thomson effect i.e., a throttling process is a constant __________ process.
- entropy
- temperature
- internal energy
- enthalpy
enthalpy
In the equation, PVⁿ = Constant, if the value of n = 0, then it represents a reversible __________ process.
- isobaric
- isothermal
- isentropic
- isometric
isobaric
Work done in an adiabatic process between two states depends on the
- rate of heat transmission
- initial state only
- end states only
- none of these
end states only
The number of degree of freedom for an azeotropic mixture of ethanol and water in vapour-liquid equilibrium, is
- 3
- 1
- 2
- 0
1
The internal energy of an ideal gas is a function of its __________ only.
- molecular size
- volume
- pressure
- temperature
temperature
`At constant temperature and pressure, for one mole of a pure substance, the ratio of the free energy to the chemical potential is
- zero
- one
- infinity
- negative
one
The change in __________ is equal to the reversible work for compression in steady state flow process under isothermal condition.
- internal energy
- enthalpy
- Gibbs free energy
- Helmholtz free energy
Gibbs free energy
Work done is a
- property of the system
- path function
- point function
- state description of a system
path function
Extensive properties of a thermodynamic system depend upon the __________ of the system.
- specific volume
- temperature
- mass
- pressure
mass
Near their critical temperatures, all gases occupy volumes __________ that of the ideal gas.
- less than
- same as
- more than
- half
less than
The free energy change for a chemical reaction is given by (where, K = equilibrium constant)
- RT lnK
- -RT lnK
- -R lnK
- T lnK
-RT lnK
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.
- decreases
- increases
- remains constant
- decreases logarithmically
increases
In the reaction, H2 +I2 ⇌ 2HI, addition of an inert gas will
- increase the partial pressure of H2.
- increase the partial pressure of I2.
- increase the total pressure and hence shift the equilibrium towards the right.
- not effect the equilibrium conditions
not effect the equilibrium conditions
What is the number of degrees of freedom for liquid water in equilibrium with a mixture of nitrogen and water vapor ?
- 2
- 0
- 3
- 1
2
The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called the __________ temperature.
- critical
- Boyle
- inversion
- reduced
Boyle
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
- increase
- decrease
- remain unaltered
- increase or decrease ; depends on the particular reaction
remain unaltered
All gases above its inversion temperature, in a throttling process will show
- a heating effect.
- no change in temperature.
- a cooling effect.
- either (a) or (c).
a heating effect.
First law of thermodynamics is mathematically stated as
- dQ = dE + dW
- dQ = dE - dW
- dE = dQ + dW
- dW = dQ + dE
dQ = dE + dW
Pick out the wrong statement.
- Surface tension of a substance vanishes at critical point, as there is no distinction between liquid and vapour phases at its critical point.
- Entropy of a system decreases with the evolution of heat.
- Change of internal energy is negative for exothermic reactions.
- The accentric factor for all materials is always more than one.
The accentric factor for all materials is always more than one.
Translational kinetic energy of molecules of an ideal gas is proportional to (where, T = absolute temperature of the gas )
- T
- √T
- T²
- 1/√T
T
Equation which relates pressure, volume and temperature of a gas is called the
- equation of state
- Gibbs Duhem equation
- ideal gas equation
- none of these
equation of state
Claussius-Clayperon equation gives accurate result, when the
- vapour pressure is relatively low and the temperature does not vary over wide limits.
- vapour obeys the ideal gas law and the latent heat of vaporisation is constant.
- volume in the liquid state is negligible compared with that in the vapour state.
- all (a), (b) and (c).
all (a), (b) and (c).
The temperature at which a real gas obeys the ideal gas laws over a wide range of pressure is called __________ temperature.
- Boyle
- inversion
- critical
- reduced
Boyle
For a single component two phase mixture, the number of independent variable properties are
- two
- one
- zero
- three
one
________ law of thermodynamics ascertains the direction of a particular spontaneous process.
- Zeroth
- First
- Second
- Third
Second
At normal boiling point, molar entropy of vaporisation is __________ Joule/K°.mole.
- 72
- 92
- 142
- 192
92
For an ideal solution, the value of activity co-efficient is
- 0
- 1
- < 1
- > 1
1
The expression, nCv(T2 - T1), is for the __________ of an ideal gas.
- work done under adiabatic condition
- co-efficient of thermal expansion
- compressibility
- none of these
work done under adiabatic condition
The number of degrees of freedom at the triple point of water is
- 0
- 1
- 2
- 3
0
Which of the following is a widely used refrigerant in vapour compression refrigeration system (using large centrifugal compressor)?
- Freon
- Liquid sulphur dioxide
- Methyl chloride
- Ammonia
Freon
Internal energy is equal to the heat absorbed in case of a/an __________ process.
- constant volume
- polytropic
- adiabatic
- constant pressure
constant volume
The first law of thermodynamics is a restatement of the law of conservation of
- mass
- energy
- momentum
- none of these
energy
Joule-Thomson co-efficient for a perfect gas is
- zero
- positive
- negative
- none of these
zero
In an adiabatic process, the
- heat transfer is zero.
- temperature change is zero.
- work done is a path function.
- enthalpy remains constant.
heat transfer is zero.
A nozzle is a device, which
- increases kinetic energy and decreases pressure.
- reduces kinetic energy and increases pressure.
- reduces both kinetic energy and pressure.
- increases both kinetic energy and pressure.
increases kinetic energy and decreases pressure.
During the phase transition, __________ changes.
- pressure
- volume
- temperature
- all (a), (b) and (c)
volume
The work done in an adiabatic change in a particular gas depends upon changes in the __________ only.
- temperature
- specific heat
- volume
- pressure
temperature
In an isothermal process on an ideal gas, the pressure increases by 0.5 percent. The volume decreases by about __________ percent.
- 0.25
- 0.5
- 0.75
- 1
0.5
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)
- (atm)^Δx, when Δx is negative
- (atm)^Δx, when Δx is positive
- Dimensionless, when Δx = 0
- (atm)^Δx2, when Δx > 0
(atm)^Δx2, when Δx > 0
Pick out the correct statement.
- The available energy in an isolated system for all irreversible (real) processes decreases.
- The efficiency of a Carnot engine increases, if the sink temperature is decreased.
- The reversible work for compression in non-flow process under isothermal condition is the change in Helmholtz free energy.
- all (a), (b) and (c)
all (a), (b) and (c)
Partial molal quantities are important in the study of
- ideal gases
- ideal solutions
- non-ideal mixtures
- a pure component
non-ideal mixtures
Number of degrees of freedom for a three phase system in equilibrium comprising of three non-reacting chemical species is
- 2
- 0
- 1
- 3
2
Critical solution temperature (or the con-solute temperature) for partially miscible liquids (e.g., phenol-water) is the minimum temperature at which
- a homogeneous solution (say of phenol water) is formed.
- mutual solubility of the two liquids shows a decreasing trend.
- two liquids are completely separated into two layers.
- none of these.
a homogeneous solution (say of phenol water) is formed.
Which is not constant for an ideal gas ?
- (∂P/∂V)T
- (∂V/∂T)P
- (∂P/∂V)V
- all (a), (b) & (c)
(∂P/∂V)T
Enthalpy ‘H’ is defined as
- H = E - PV
- H = F - TS
- H - E = PV
- none of these
H - E = PV
One ton of refrigeration is defined as the heat rate corresponding to melting of one ton of ice in one
- hour
- day
- minute
- second
day
________ functions are exemplified by heat and work.
- Path
- Point
- State
- none of these
Path
In an irreversible process
- Tds = dE - dW = 0
- dE - dW - Tds = 0
- Tds - dE + dW< 0
- Tds - dT + dW< 0
Tds - dE + dW< 0
What is the number of degree of freedom for a system of two miscible non-reacting species in vapor-liquid equilibrium forming an azeotrope ?
- 3
- 2
- 1
- 0
1
The entropy change in a reversible isothermal process, when an ideal gas expands to four times its initial volume is
- R logₑ 4
- R log10 4
- Cv log10 4
- Cv logₑ 4
R logₑ 4
PV^γ = Constant (where, γ = Cp/Cv) is valid for a/an __________ process.
- isothermal
- isentropic
- isobaric
- adiabatic
adiabatic
Claude gas liquefaction process employs cooling
- at constant pressure.
- by throttling.
- by expansion in an engine.
- none of these.
by expansion in an engine.
The heat capacities for the ideal gas state depend upon the
- pressure
- temperature
- both (a) & (b)
- neither (a) nor (b)
temperature
Which of the following will increase the volume of a real gas by four times ?
- Doubling the absolute temperature as well as pressure of the gas.
- Reducing pressure to one fourth at constant temperature.
- Reducing temperature to one fourth at constant pressure.
- Reducing the temperature to half and doubling the pressure.
Reducing pressure to one fourth at constant temperature.
Pick out the wrong statement.
- A refrigeration cycle violates the second law of thermadynamics.
- Refrigeration cycle is normally represented by a temperature vs. entropy plot.
- In a refrigerator, work required decreases as the temperature of the refrigerator and the temperature at which heat is rejected increases.
- One ton of refrigeration is equivalent to the rate of heat absorption equal to 3.53 kW.
A refrigeration cycle violates the second law of thermadynamics.
The equation, PV = nRT, is best obeyed by gases at
- low pressure & high temperature.
- high pressure & low temperature.
- low pressure & low temperature.
- none of these.
low pressure & high temperature.
Internal energy of an element at 1 atm and 25° C is __________ kcal/kg.mole.
- 0
- 273
- 25
- none of these
0
Which of the following liquid metals has the highest thermal conductivity ?
- Molten sodium
- Molten lead
- Mercury
- Molten potassium
Molten sodium
Which of the following has the least thermal efficiency ?
- Steam engine
- Carnot engine
- Diesel engine
- Otto engine
Steam engine
Joule-Thomson Co-efficient at any point on the inversion curve is
- ∞
- +ve
- 0
- -ve
0
Pick out the wrong statement.
- The values of (∂P/∂V)T and (∂²P/∂V²)T are zero for a real gas at its critical point.
- Heat transferred is equal to the change in the enthalpy of the system, for a constant pressure, non-flow, mechanically reversible process.
- Thermal efficiency of a Carnot engine depends upon the properties of the working fluid besides the source & sink temperatures.
- During a reversible adiabatic process, the entropy of a substance remains constant.
Thermal efficiency of a Carnot engine depends upon the properties of the working fluid besides the source & sink temperatures.
Number of components (C), phase (P) and degrees of freedom (F) are related by Gibbs phase rule as
- P + F - C = 2
- C = P - F + 2
- F = C - P - 2
- P = F - C - 2
P + F - C = 2
The value of Cp & Cv respectively for monoatomic gases in Kcal/kg Mole . °K are
- 5 & 3
- 3.987 & 1.987
- 1.987 & 0.66
- 0.66 & 1.987
5 & 3
(∂T/∂P)H is the mathematical expression for
- specific heat at constant pressure (Cp).
- specific heat at constant volume (Cv).
- Joule-Thompson co-efficient.
- none of these.
Joule-Thompson co-efficient.
In case of a close thermodynamic system, there is __________ across the boundaries.
- no heat and mass transfer
- no mass transfer but heat transfer
- mass and energy transfer
- none of these
no mass transfer but heat transfer
During a reversible isothermal expansion of an ideal gas, the entropy change is
- +ve
- 0
- -ve
- ∞
- +ve
As the temperature is lowered towards the absolute zero, the value of ∂(ΔF)/∂T, then approaches
- unity
- zero
- that of the heat of reaction
- infinity
zero
The ratio of equilibrium constants (Kp2/Kp1) at two different temperatures is given by
Which of the following is not affected by temperature changes ?
- Fugacity
- Activity co-efficient
- Free energy
- None of these
None of these
For an ideal gas, the activity co-efficient is
- directly proportional to pressure.
- inversely proportional to pressure.
- unity at all pressures.
- none of these.
unity at all pressures.
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.
- ideal
- real
- isotonic
- none of these
ideal
Consider the process A & B shown in the figure given below:
In this case, it is possilbe that
- both the processes are adiabatic.
- both the processes are isothermal.
- process A is isothermal while B is adiabatic.
- process A is adiabatic while B is isothermal.
process A is isothermal while B is adiabatic.
Pick out the wrong statement.
- System (of partially miscible liquid pairs), in which the mutual solubility increases with rise in temperature, are said to possess an upper consolute temperature.
- Systems, in which the mutual solubility increases with decrease in temperature, are said to possess lower consolute temperature.
- 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.
- none of these
none of these
Which of the following is not an intensive property ?
- Volume
- Density
- Temperature
- Pressure
Volume
Heat is added at constant temperature in an ideal __________ cycle.
- Stirling
- Brayton
- Rankine
- none of these
Stirling
The root mean square speed of molecules of a gas is equal to (where, m = mass of the molecule K = Boltzman’s constant, T = absolute temperature)
Efficiency of a Carnot engine working between temperatures T1 and T2 (T1 < T) is
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.
The net work done during the complete cycle is given by the area covered by
P₁ACBP₂P₁
ACBB¹A¹A
ACBDA
ADBB¹A¹A
ACBDA
During adiabatic expansion of gas
- pressure remains constant.
- pressure is increased.
- temperature remains constant.
- none of these.
none of these.
Change of heat content when one mole of compound is burnt in oxygen at constant pressure is called the
- calorific value
- heat of reaction
- heat of combustion
- heat of formation
heat of combustion
In which of the following reaction equilibria, the value of equilibrium constant Kp will be more than is Kc ?
- 2HI ⇌ H2 + I2
- N2O4 ⇌ 2NO2
- 2SO2 + O2 ⇌ 2SO3
- none of these
N2O4 ⇌ 2NO2
Maxwell’s relation corresponding to the identity, dH = dS = Vdp + ∑μi dni is
Heat requirement for decomposition of a compound into its elements is __________ that is evolved during the formation of that compound from its elements.
- the same
- less than
- greater than
- different than
the same
The unit of equilibrium constant of a chemical reaction is the same as that of
- molar concentration
- temperature
- internal energy
- none of these
none of these
Which of the following equations is obtained on combining 1st and 2nd law of thermodynamics, for a system of constant mass?
- dE = Tds - PdV
- dQ = CvdT + PdV
- dQ = CpdT + Vdp
- Tds = dE - PdV
dE = Tds - PdV
Entropy is a/an
- state function
- macroscopic property
- extensive property
- none of these
none of these
true ans: extensive property
Which of the following is not correct for a reversible adiabatic process ?
- TV^γ-1 = constant
- p^(1-γ).T^γ = constant
- PV^γ = constant
- none of these
none of these
true ans: * p^(1-γ).T^γ = constant
The difference between isothermal compressibility and adiabatic compressibility for an ideal gas is
- 0
- +ve
- -ve
- ∞
+ve
It is desired to bring about a certain change in the state of a system by performing work on the system under adiabatic conditions.
- The amount of work needed is path dependent.
- Work alone can not bring out such a change of state.
- The amount of work needed is independent of path.
- More information is needed to conclude anything about the path dependence or otherwise of the work needed.
The amount of work needed is path dependent.
Pick out the Claussius-Clayperon equation from the following:
For organic compounds, group contribution method can be used for the estimation of
- critical properties.
- specific gravity.
- specific volume.
- thermal conductivity.
critical properties.
Specific ________ does not change during phase change at constant temperature and pressure.
- entropy
- Gibbs energy
- internal energy
- enthalpy
Gibbs energy
Heat evolved/absorbed during conversion of a substance from one allotropic form to another is termed as the heat of
- fusion
- vaporisation
- transition
- none of these
transition
The efficiency of an Otto engine compared to that of a diesel engine, for the same compression ratio will be
- more
- less
- same
- data insufficient to predict
more
The fusion of a crystalline solid at its melting point to form a liquid at the same temperature is accompanied by
- decrease in enthalpy corresponding to evolution of heat.
- decrease of entropy.
- increase in enthalpy corresponding to absorption of heat.
- no change in enthalpy.
increase in enthalpy corresponding to absorption of heat.
Melting of ice is an example of an __________ process.
- adiabatic
- isothermal
- isometric
- none of these
isothermal
Gibbs-Helmholtz equation is
Pick out the wrong statement.
- The net change in entropy in any reversible cycle is always zero.
- The entropy of the system as a whole in an irreversible process increases.
- The entropy of the universe tends to a maximum.
- The entropy of a substance does not remain constant during a reversible adiabatie change.
The entropy of a substance does not remain constant during a reversible adiabatie change.
Pick out the wrong statement.
- At constant pressure, solubility of a gas in a liquid diminishes with rise in temperature.
- Normally, the gases which are easily liquified, are more soluble in common solvents.
- The gases which are capable of forming ions in aqueous solution, are much more soluble in water than in other solvents.
- At constant pressure, solubility of a gas in a liquid increases with rise in temperature.
At constant pressure, solubility of a gas in a liquid diminishes with rise in temperature.
Gibbs phase rule finds application, when heat transfer occurs by
- conduction
- convection
- radiation
- condensation
condensation
For a reversible process involving only pressure-volume work
- (dF)T, p < 0
- (dF)T, p > 0
- (dF)T, p = 0
- (dA)T, v < 0
(dF)T, p = 0
true ans: (dA)T, v < 0
An ideal monoatomic gas is taken round the cycle ABCDA as shown below in the P-V diagram
The work done during the cycle is
- PV
- 2PV
- PV/2
- 0
PV
One ton of refrigeration capacity is equivalent to the heat removal rate of
- 50 k cal/hr
- 200 BTU/hr
- 200 BTU/minute
- 200 BTU/day
200 BTU/minute
The second law of thermodynamics states that
- the energy change of a system undergoing any reversible process is zero.
- it is not possible to transfer heat from a lower temperature to a higher temperature.
- the total energy of system and surrounding remains the same.
- none of the above.
none of the above.
true ans: it is not possible to transfer heat from a lower temperature to a higher temperature.
Internal energy of an ideal gas
- increases with increase in pressure.
- decreases with increase in temperature.
- is independent of temperature.
- none of these.
none of these.
Pick out the wrong statement.
- The conversion for a gas phase reaction increases with decrease in pressure, if there is an increase in volume accompanying the reaction.
- With increase in temperature, the equilibrium constant increases for an exothermic reaction.
- The equilibrium constant of a reaction depends upon temperature only.
- The conversion for a gas phase reaction increases with increase in pressure, if there is a decrease in volume accompanying the reaction.
With increase in temperature, the equilibrium constant increases for an exothermic reaction.
The adiabatic throttling process of a perfect gas is one of constant enthalpy
- in which there is a temperature drop.
- which is exemplified by a non-steady flow expansion.
- which can be performed in a pipe with a constriction.
- in which there is an increase in temperature.
which can be performed in a pipe with a constriction.
A gas performs the maximum work, when it expands
- non-uniformly
- adiabatically
- isobarically
- isothermally
isobarically
true ans: isothermally
Which of the following is Virial equation of state?
- (p + a/V^2)(V - b) = nRT
- PV = nRT
- PV = A + B/V + C/V^2 + D/V^3 + …
- T = RT/(V-b) - a/[√T.V(V+b)]
PV = A + B/V + C/V^2 + D/V^3 + …
Henry’s law is closely obeyed by a gas, when its ________ is extremely high.
- pressure
- solubility
- temperature
- none of these
none of these
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
- the distribution law.
- followed from Margule’s equation.
- a corollary of Henry’s law.
- none of these.
the distribution law.
A solid is transformed into vapour without going to the liquid phase at
- triple point
- boiling point
- below triple point
- always
triple point
true ans: below triple point
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
- 35 K
- 174 K
- 274 K
- 154 K
274 K
true ans: 174 K
For a thermodynamic system containing ‘x’ chemical species, the maximum number of phases that can co-exist at equilibrium is
- x
- x + 1
- x + 2
- x + 3
x + 2
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
- temperature only.
- temperature and pressure only.
- temperature, pressure and liquid composition xi only.
- temperature, pressure, liquid composition xi and vapour composition yi.
temperature, pressure and liquid composition xi only.
‘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
- the statement as per Gibbs-Helmholtz
- called Lewis-Randall rule
- Henry’s law
- none of these
called Lewis-Randall rule
Which one is true for a throttling process ?
- A gas may have more than one inversion temperatures.
- The inversion temperature is different for different gases.
- The inversion temperature is same for all gases.
- The inversion temperature is the temperature at which Joule-Thomson co-efficient is infinity.
The inversion temperature is different for different gases.
Chemical potential of ith component of a system is given by
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
- 30554
- 10373
- 4988.4
- 4364.9
10373
true ans: 4364.9
Lenz’s law results from the law of conservation of
- mass
- momentum
- energy
- none of these
energy
Charles’ law for gases states that
- V/T = Constant
- V ∝ 1/T
- V ∝ 1/P
- PV/T = Constant
V/T = Constant
As pressure approaches zero, the ratio of fugacity to pressure (f/P) for a gas approaches
- zero
- unity
- infinity
- an indeterminate value
unity
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
- 1.572
- 1.9398
- 3.389
- 4.238
1.572
The variation of heat of reaction with temperature at constant pressure is given by the __________ law.
- Kelvin’s
- Antonie’s
- Kirchoffs
- none of these
Kirchoffs
Which of the following equations is used for the prediction of activity co-efficient from experiments ?
- Van Laar equation
- Margules equation
- Wilson’s equation
- all (a), (b) and (c)
all (a), (b) and (c)
The equation below is applicable to a binary solution of components. A and B in equilibrium with their vapors at constant temperature and pressure is called the __________ equation.
- Van Laar
- Margules
- Gibbs-Duhem
- Gibbs-Duhem-Margules
Gibbs-Duhem-Margules
Entropy of a substance remains constant during a/an __________ change.
- reversible isothermal
- irreversible isothermal
- reversible adiabatic
- none of these
reversible adiabatic
Which of the following represents the Virial equation of state ?
The equilibrium constant for a chemical reaction at two different temperatures is given by
For a constant volume process ________ by the system is used only to increase the internal energy.
- heat absorbed
- work done
- both (a) & (b)
- neither (a) nor (b)
heat absorbed
When a system is in equilibrium for all possible processes, the differential or finite change of entropy is
- < 0
- > 0
- = 0
- none of these
< 0
true ans: = 0
A system is said to be at equilibrium, if the entropy of the system has reached __________ value.
- minimum
- zero
- maximum
- none of these
maximum
In the equation, PV^n = constant, if the value of n = ± ∞, then it represents a reversible __________ process.
- adiabatic
- isometric
- isentropic
- isothermal
isometric
In an ideal gas mixture, fugacity of a species is equal to its
- vapor pressure
- partial pressure
- chemical potential
- none of these
partial pressure
Joule-Thomson co-efficient is defined as
For an ideal liquid solution, which of the following is unity ?
- Activity
- Fugacity
- Activity co-efficient
- Fugacity co-efficient
Activity co-efficient
In the decomposition of PCl5 represented by, PCl5 ⇌ PCl3 + Cl2, decrease in the pressure of the system will ________ the degree of dissociation of PCl5.
- increase
- decrease
- not alter
- none of these
increase
In case of an __________ process, the temperature of the system increases.
- isothermal compression
- isothermal expansion
- adiabatic expansion
- adiabatic compression
adiabatic compression
Cp of a gas at its critical temperature and pressure
- becomes zero.
- becomes infinity.
- equals 1 kcal/kmol °K.
- equals 0.24 kcal/kmol °K.
becomes infinity.
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 )
λb/Tb
Tb/λb
√(λb/Tb)
√(Tb/λb)
λb/Tb
Which of the following is true for Virial equation of state ?
- Virial co-efficients are universal constants.
- Virial co-efficients ‘B’ represents three body interactions.
- Virial co-efficients are function of temperature only.
- For some gases, Virial equations and ideal gas equations are the same.
Virial co-efficients are function of temperature only.
Molar heat capacity of water in equilibrium with ice at constant pressure is __________ Kcal/kg mole . °K
- 0
- ∞
- 50
- 100
∞
A gas can be liquified by pressure alone only, when its temperature is __________ its critical temperature.
- less than
- more than
- equal to or higher than
- less than or equal to
less than or equal to
Thermal efficiency of a Carnot engine can approach 100%, only when the temperature of the
- cold reservoir approaches zero.
- hot reservoir approaches infinity.
- either (a) or (b).
- neither (a) nor (b).
either (a) or (b).
Compound having large heat of formation is
- more stable.
- less stable.
- not at all stable (like nascent O2).
- either more or less stable ; depends on the compound.
more stable.
