ChE 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
W = PΔV
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
The second law of thermodynamics states that heat cannot spontaneously flow from a cold body to a hot body.
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
COP = Qc/W. The work removed from the cold reservoir is always greater than the work required to operate the ref.
_________ increases with increase in pressure.
The melting point of wax
The boiling point of a liquid
both (a) and (b)
neither (a) nor (b)
both (a) and (b)
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
Dependent on mass as unit is J/g*°C. The intensive property is the specific 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
↑COP ↑efficiency:
Air cycle < ordinary vapor < vapor compression < carnot
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
Entropy of an ideal gas depends upon its
pressure
temperature
both (a) & (b)
neither (a) nor (b)
both (a) & (b)
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
W = PΔV
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
df = 2 - P + C
df = 2 - 3 + 1
“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
↑COP ↑efficiency:
Air cycle < ordinary vapor < vapor compression < carnot
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
ΔG = ΔF - TΔS
ΔG = ΔA - PΔV
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 = nRTln(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.
It should be 1.
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
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
activity
Free energy change at equilibrium is
zero
positive
negative
indeterminate
zero
Heat pump
accomplishes only space heating in winter.
accomplishes only space cooling in summer.
accomplishes both (a) and (b).
works on Carnot cycle.
accomplishes both (a) and (b).
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
not used anymore due to ozone depleting ability
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
Entropy change of mixing two liquid substances depends upon the
molar concentration
quantity (i.e. number of moles)
both (a) and (b)
neither (a) nor (b)
both (a) and (b)
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.
Heat capacity is affected by the state of the substance. Ex: c_h2o and c_ice is different.
The principle applied in liquefaction of gases is
adiabatic expansion.
Joule-Thomson effect.
both (a) and (b).
neither (a) nor (b).
both (a) and (b).
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
df = 2 - P + C - a
df = 2 - 2 + 2 - 1
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 (𝛅V/𝛅T)_P is the mathematical expression of ____.
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
A 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.
Mollier diagram is a plot of
temperature vs. enthalpy
temperature vs. enthalpy
entropy vs. enthalpy
temperature vs. internal energy
entropy vs. enthalpy
(𝛅E/𝛅T)_V 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
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
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
(𝛅H/𝛅T)_P is the mathematical expression for
CV
entropy change
Gibbs free energy
none of these
none of these
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.
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 idea] 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.
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)
The standard Gibbs free energy change of a reaction depends on the equilibrium
pressure
temperature
composition
all (a), (b) and (c)
temperature
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.
Gibbs free energy (G) is represented by, G= H - TS, whereas Helmholtz free energy, (A) is given by, A =E - TS. Which of the following is the Gibbs-Helmholtz equation
[ϑ(G/T)/ϑT] = -H/T^2
[ϑ(A/T)/ϑT]v = -E/T^2
both (a) and (b)
neither (a) nor (b)
both (a) and (b)
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 en-dothermic 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, [eqn] , 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/RT^2
dlnp/dt = RT^2/Hvap
dp/dt = RT^2/Hvap
dP/dT = Hvapor/RT^2
dlnp/dt = Hvap/RT^2
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
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
If an ideal solution is formed by mixing two pure liquids in any proportion, then the __________ of mixing is zero.
enthalpy
volume
both ‘a’ & ‘b’
neither ‘a’ nor ‘b’
both ‘a’ & ‘b’
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
T^2
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
The value of gas constant ‘R’ is
1.987 cal/gm mole °K
1.987 BTU/lb. mole °R
both (a) and (b)
neither (a) nor (b)
both (a) and (b)
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 ?
(ϑP/ϑV)_T
(ϑV/ϑT)_P
(ϑP/ϑV)_V
all (a), (b) & (c)
(ϑP/ϑV)_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
PVγ = Constant (where, γ = Cp/Cv) is valid for a/an __________ process.
isothermal
isentropic
isobaric
adiabatic
adiabatic
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 refriferation 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 refriferation 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 (ϑP/ϑV)_T and (ϑ2P/ϑV2)_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
(ϑT/ϑP)_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 ϑ(ΔF)/ϑT, 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
R/ΔH[1/T1-1/T2]
ΔH/R[1/T1-1/T2]
ΔH/R[1/T2-1/T1]
1/R[1/T1-1/T2]
ΔH/R[1/T1-1/T2]
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
Generation of heat by friction is an example of a/an __________ change.
isothermal
irreversible
adiabatic
reversible
irreversible
A domestic refrigerator has a/an __________ cooled condenser.
water
air
evaporative
gas
air
The extensive properties are
volume, mass and number of moles.
free energy, entropy and enthalpy.
both (a) and (b).
none of these.
both (a) and (b).
The compressibility factor of a gas is given by (where, V1 = actual volume of the gas V2 = gas volume predicted by ideal gas law )
V1/V2
V2/V1
V1-V2
V1.V2
V1/V2
If we increase the pressure on a substance (which is at its triple point), then the triple point
increases
decreases
remains unchanged
may increase or decrease ; depends on the substance
remains unchanged
In an ideal refrigeration cycle, the change in internal energy of the fluid is
+ve
-ve
0
either of the above three ; depends on the nature of refrigerant.
0
Free energy
decreases in all spontaneous (or irreversible) processes.
change during a spontaneous process has a negative value.
remains unchanged in reversible processes carried at constant temperature and pressure.
all (a), (b) and (c).
all (a), (b) and (c).
“If different processes are used to bring about the same chemical reaction, the enthalpy change is same for all of them”. This is __________ law.
Hess’s
Kirchoff’s
Lavoisier and Laplace
none of these
Hess’s
Fugacity is a measure of the
escaping tendencies of the same substance in different phases of a system.
relative volatility of a mixture of two miscible liquids.
behaviour of ideal gases.
none of these.
escaping tendencies of the same substance in different phases of a system.
The quantitative effect of temperature on chemical equilibrium is given by the
Vant-Hoff equation.
Le-Chatelier’s principle.
Arhenius equation.
none of these.
Vant-Hoff equation.
For an irreversible 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
Ideal refrigeration cycle is
same as Carnot cycle.
same as reverse Carnot cycle.
dependent on the refrigerant’s properties.
the least efficient of all refrigeration processes.
same as reverse Carnot cycle.
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
100, 000 kW
160, 000 kW
200, 000 kW
320, 000 kW
320, 000 kW
Refrigeration cycle
violates second law of thermodynamics.
involves transfer of heat from low temperature to high temperature.
both (a) and (b).
neither (a) nor (b).
involves transfer of heat from low temperature to high temperature.
The enthalpy change when ammonia gas is dissolved in water is called the heat of _____.
solution
formation
dilution
combustion
solution
The value of Joule-Thomson co-efficient, in case where cooling occurs after the throttling process is
0
∞
+ve
-ve
+ve
The specific heat of saturated water vapour at 100°C is
∞
-ve
0
+ve
-ve
For a multicomponent system, the term chemical potential is equivalent to the
molal concentration difference.
molar free energy.
partial molar free energy.
molar free energy change.
partial molar free energy.
The change in Gibbs freee energy for vaporisation of a pure substance is
positive
negative
zero
may be positive or negative
zero
Critical compressibility factor for all substances
are more or less constant (vary from 0.2 to 0.3).
vary as square of the absolute temperature.
vary as square of the absolute pressure.
none of these.
are more or less constant (vary from 0.2 to 0.3).
What is the degree of freedom for two mis-cible (non-reacting) substances in vapor-liquid equilibrium forming an azeotrope ?
0
1
2
3
2
For a given substance at a specified temperature, activity is __________ to fugacity.
directly proportional
inversely proportional
equal
none of these
directly proportional
In case of vapour compression refrigeration system, elevating the evaporator temperature (keeping the condenser temperature constant) results in ______.
enhanced COP.
decreased COP.
no change in the value of COP.
increased or decreased COP ; depending upon the type of refrigerant.
enhanced COP.
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 cm3 and that in vapour phase in 391.1 cm3.Fugacity of water (in kPa) at 9000 kPa will be
6738.9
6753.5
7058.3
9000
6753.5
As the temperature is lowered towards the absolute zero, the value of the quantity (ϑΔF/ϑT) approaches
zero
unity
infinity
none of these
zero
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
solubility increases as temperature increases.
solubility increases as temperature decreases.
solubility is independent of temperature.
solubility increases or decreases with temperature depending on the Gibbs free energy change of solution.
solubility increases as temperature decreases.
In case of a reversible process (following pvn = constant), work obtained for trebling the volume (v1 = 1 m3 and v2 3 m3 ) is max imum, when the value of ‘n’ is
0
1
y = 1.44
1.66
0
The Carnot co-efficient of performance (COP) of a domestic air conditioner compared to a household refrigerator is
less
more
same
dependent on climatic conditions
less
The unit of fugacity is the same as that of the
pressure
temperature
volume
molar concentration
pressure
Filling of gas from a high pressure cylinder into small bottles is an example of a/an __________ process.
equilibrium
adiabatic
steady
unsteady
unsteady
A large iceberg melts at the base, but not at the top, because of the reason that
ice at the base contains impurities which lowers its melting point.
due to the high pressure at the base, its melting point reduces.
the iceberg remains in a warmer condition at the base.
all (a), (b) and (c).
due to the high pressure at the base, its melting point reduces.
At the critical point of a substance
the surface tension vanishes.
liquid and vapour have the same density.
there is no distinction between liquid and vapour phases.
all (a), (b) and (c).
all (a), (b) and (c).
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)
Δ S1 is always < Δ SR
Δ S1 is sometimes > Δ SR
Δ S1 is always > Δ SR
Δ S1 is always = Δ SR
Δ S1 is always > Δ SR
What is the value of Joule-Thomson co-efficient for an ideal gas ?
+ve
-ve
0
∞
0
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)
logarithmic
arithmetic
geometric
harmonic
geometric
y = specific heat ratio of an ideal gas is equal to
Cp/Cv
Cp/(CP-R)
1 + (R/CV)
all (a), (b) and (c)
all (a), (b) and (c)
Gibbs free energy of a pure fluid approaches __________ as the pressure tends to zero at constant temperature.
infinity
minus infinity
zero
none of these
minus infinity
As the entropy of the universe is increasing, day by day, the work producing capacity of a heat engine is
not changed
decreasing
increasing
data sufficient, can’t be predicted
decreasing
An irreversible process
is the analog of linear frictionless motion in machines.
is an idealised visualisation of behaviour of a system.
yields the maximum amount of work.
yields an amount of work less than that of a reversible process.
yields an amount of work less than that of a reversible process.
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.
isobaric
isothermal
adiabatic
none of these
isothermal
Joule-Thomson co-efficient depends on the
pressure.
temperature.
both (a) & (b).
neither (a) nor (b).
both (a) & (b).
Free energy change of mixing two liquid substances is a function of the
concentration of the constituents only.
quantities of the constituents only.
temperature only.
all (a), (b) and (c).
all (a), (b) and (c).
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
The total change in the enthalpy of a system is independent of the
number of intermediate chemical reactions involved.
pressure and temperature.
state of combination and aggregation in the beginning and at the end of the reaction.
none of these.
number of intermediate chemical reactions involved.
Number of phases in a colloidal system are
1
2
3
4
2
Free energy changes for two reaction mechanism ‘X’ and ‘Y are respectively - 15 and - 5 units. It implies that X is
slower than Y
faster than Y
three times slower than Y
three times faster than Y
faster than Y
Vapour which is at a pressure smaller than the saturation pressure for the temperature involved is called a __________ vapour.
superheated
desuperheated
non-condensable
none of these
superheated
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.)
μ° + RT ln f
μ°+ R lnf
μ° + T lnf
μ° + R/T lnf
μ° + RT ln f
The kinetic energy of gas molecule is zero at
0°C
273°C
100°C
-273°C
-273°C
Which of the following is not an intensive property ?
Volume
Density
Temperature
Pressure
Volume
The necessary and sufficient condition for equilibrium between two phases is
the concentration of each component should be same in the two phases.
the temperature of each phase should be same.
the pressure should be same in the two phases.
the chemical potential of each component should be same in the two phases.
the chemical potential of each component should be same in the two phases.
Specific volume of an ideal gas is
equal to its density.
the reciprocal of its density.
proportional to pressure.
none of these.
the reciprocal of its density.
Pick out the extensive property out of the following.
Surface tension
Free energy
Specific heat
Refractive index
Free energy
Entropy change of the reaction, H2O(liquid) H2O(gas), is termed as the enthalpy of
solution
vaporisation
formation
formation
vaporisation
Which law of the thermodynamics provids basis for measuring the thermodynamic property ?
First law
Zeroth law
Third law
Second law
Zeroth law
Gibbs free energy per mole for a pure substance is equal to the
latent heat of vaporisation
chemical potential
molal boiling point
heat capacity
chemical potential
Gibbs free energy at constant pressure and temperature under equilibrium conditions is
∞
0
maximum
minimum
minimum
With increase in pressure (above atmospheric pressure), the Cp of a gas
increases
decreases
remains unchanged
first decreases and then increases
increases
A change in state involving a decrease in entropy can be spontaneous, only if
it is exothermic.
it is isenthalpic.
it takes place isothermally.
it takes place at constant volume.
it is exothermic.
Joule-Thomson co-efficient which is defined as, n = (ϑT/ϑP)_H = 1/Cp(ϑH/ϑT)_P, changes sign at a temperature known as inversion temperature. The value of Joule-Thomson co-efficient at inversion temperature is
0
∞
+ve
-ve
0
__________ calorimeter is normally used for measuring the dryness fraction of steam, when it is very low.
Bucket
Throttling
Separating
A combination of separating & throttling
A combination of separating & throttling
The amount of heat required to decompose a compound into its elements is __________ the heat of formation of that compound from its elements.
less than
more than
same as
not related to
same as
For a constant volume process
dE = CpdT
dE = CvdT
dQ = dE + pdV
dW = pdV
dE = CvdT
In case of the decomposition of hydroiodic acid (2HI → H2 + I2), addition of H2 (at equilibrium condition) will ____.
increase the partial pressure of I2.
decrease the partial pressure of HI.
diminish the degree of dissociation of HI.
none of these.
diminish the degree of dissociation of HI.
In any spontaneous process, the __________ free energy decreases.
Helmholtz
Gibbs
both a & b
neither ‘a’ nor ‘b’
both a & b
The gas law (PV = RT) is true for an __________ change.
isothermal
adiabatic
both (a) & (b)
neither (a) nor (b)
both (a) & (b)
The equation DU = Tds - PdV is applicable to infinitesimal changes occuring in
an open system of constant composition.
a closed system of constant composition.
an open system with changes in composition.
a closed system with changes in composition.
a closed system with changes in composition.
Heat is added at constant temperature in an ideal __________ cycle.
Stirling
Brayton
Rankine
none of these
Stirling
Pick out the correct equation relating ‘F’ and ‘A’.
F = A + PV
F = E + A
F = A - TS
F = A + TS
F = A + PV
In a reversible process
Tds = dE + dW
dE - dW = Tds
dW - dE = Tds
Tds - dW + dE >0
Tds = dE + dW
Cv for an ideal gas
does not depend upon temperature.
is independent of pressure only.
is independent of volume only.
is independent of both pressure and volume.
is independent of both pressure and volume.
The equation, Cp - Cv = R, is true for __________ gas.
no
any real
only ideal
both (b) and (c)
only ideal
In a homogeneous solution, the activity co-efficient of a component depends upon the
pressure
composition
temperature
all (a), (b) and (c)
all (a), (b) and (c)
Pick out the wrong statement:
The expansion of a gas in vacuum is an irreversible process.
An isometric process is a constant pressure process.
Entropy change for a reversible adiabatic process is zero.
Free energy change for a spontaneous process is negative.
An isometric process is a constant pressure process.
With increase in compression ratio, the efficiency of the otto engine
increases
decreases
remains constant
increases linearly
increases
The chemical potential of any constituent of an ideal solution depends on the __________ of the solution.
temperature
pressure
composition
all (a), (b) and (c)
all (a), (b) and (c)
Fugacity and pressure are numerically equal, when the gas is
in standard state
at high pressure
at low temperature
in ideal state
in ideal state
Refrigerants commonly used for domestic refrigerators are
ethyl chloride or methyle chloride
freon-12
propane
NH3 or CO2.
ethyl chloride or methyle chloride
Absolute zero temperature signifies the
minimum temperature attainable.
temperature of the heat reservoir to which a Carnot engine rejects all the heat that is taken in.
temperature of the heat reservoir to which a Carnot engine rejects no heat.
none of these.
temperature of the heat reservoir to which a Carnot engine rejects no heat.
Specific __________ does not change during a phase change (e.g. sublimation, melting, vaporisation etc.).
entropy
internal energy
enthalpy
Gibbs free energy
Gibbs free energy
Heat of formation of an element in its standard state is
0
< 0
> 0
a function of pressure
0
The equation relating E, P, V and T which is true for all substanes under all conditions is given by .This equation is called the
Maxwell’s equation.
thermodynamic equation of state.
equation of state.
Redlich-Kwong equation of state.
thermodynamic equation of state.
For an exothremic reaction
only enthalpy change (ΔH) is negative.
only internal energy change (ΔE) is negative.
both ΔH and ΔE are negative.
enthalpy change is zero.
both ΔH and ΔE are negative.
Pick out the wrong statement.
An ideal liquid or solid solution is defined as one in which each component obeys Raoult’s law.
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.
Henry’s law is rigorously correct in the limit of infinite dilution.
none of these.
none of these.
The shape of T-S diagram for Carnot Cycle is a
rectangle
rhombus
trapezoid
circle
rectangle
For an isothermal process, the internal energy of a gas
increases
decreases
remains unchanged
data insufficient, can’t be predicted
remains unchanged
In the equation, PVn = constant, if the value of n = 1, then it represents a reversible __________ process.
isothermal
isobaric
polytropic
adiabatic
isothermal
For the gaseous phase chemical reaction, C2H4(g) + H2O(g) C2H5OH(g), the equilibrium conversion does not depend on the
steam to ethylene ratio.
temperature.
pressure.
none of these.
none of these.
The first law of thermodynamics is a statement of conservation of
heat
momentum
energy
work
energy
“Dry ice” is
moisture free ice
solid helium
solid carbon dioxide
none of these
solid carbon dioxide
Cv is given by
(ϑE/ϑT)_V
(ϑE/ϑV)_T
(ϑE/ϑP)_V
(ϑV/ϑT)_P
(ϑE/ϑT)_V
Which of the following non-flow reversible compression processes require maximum work ?
Adiabatic process
Isothermal process
Isobaric process
All require same work
Adiabatic process
Pick out the correct statement.
A real gas on expansion in vacuum gets heated up.
An ideal gas on expansion in vacuum gets cooled.
An ideal gas on expansion in vacuum gets heated up.
A real gas on expansion in vacuum cools down whereas ideal gas remains unaffected.
A real gas on expansion in vacuum cools down whereas ideal gas remains unaffected.
“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
Le-Chatelier principle.
Kopp’s rule.
law of corresponding state.
Arrehenius hypothesis.
Le-Chatelier principle.
Sound waves propagation in air exemplifies an __________ process.
adiabatic
isothermal
isometric
none of these
adiabatic
For equilibrium process (i.e. reversible) in an isolated system
ds = 0
ds < 0
ds > 0
ds = Constant
ds = 0
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
T
T and P
T, P and Z
T and Z
T and P
With increase in reduced temperature, the fugacity co-efficient of a gas at constant reduced pressure
increases
decreases
remains same
decreases linearly
increases
For an ideal gas, the enthalpy
increases with rise in pressure.
decreases with rise in pressure.
is independent of pressure.
is a path function.
is independent of pressure.
Efficiency of a heat engine working on Carnot cycle between two temperature levels depends upon the _____.
two temperatures only.
pressure of working fluid.
mass of the working fluid.
mass and pressure both of the working fluid.
two temperatures only.
In Joule-Thomson porous plug experiment, the
enthalpy does not remain constant.
entire apparatus is exposed to surroundings.
temperature remains constant.
none of these.
none of these.
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)
√2KT/m
√3KT/m
√6KT/m
3KT/m
√3KT/m
The intensive properties are
molar volume, density, viscosity and boiling point.
refractive index and surface tension.
both (a) and (b).
none of these.
both (a) and (b).
A Carnot cycle consists of the following steps :
Two isothermals and two isentropics.
Two isobarics and two isothermals.
Two isochorics and two isobarics.
Two isothermals and two isochorics.
Two isothermals and two isentropics.
For a cyclic process, a fixed ratio between heat and work
always exists
may exist
never exists
is difficult to predict
always exists
Which of the following is not a common refrigerant ?
Freon-12
Ethylene
Ammonia
Carbon dioxide
Ethylene
The most important application of distribution law is in
evaporation
liquid extraction
drying
distillation
liquid extraction
Pick out the correct statement.
Entropy and enthalpy are path functions.
In a closed system, the energy can be exchanged with the surrounding, while. matter can not be exchanged.
All the natural processes are reversible in nature.
Work is a state function.
All the natural processes are reversible in nature.
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
5.2
6.2
0.168
data insufficient, can’t be found out
5.2
Gibbs free energy of mixing at constant pressure and temperature is always
0
∞
+ ve
- ve
- ve
The compressibility factor for an ideal gas is 1. Its value for any other real gas is
1
< 1
> 1
either (b) or (c), depends on the nature of the gas
either (b) or (c), depends on the nature of the gas
If two gases have same reduced temperature and reduced pressure, then they will have the same
volume
mass
critical temperature
none of these
none of these
Which of the following is an extensive property of a system ?
Heat capacity
Molal heat capacity
Pressure
Concentration
Heat capacity
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
1
2
3
0
2
Cp - Cv = R is valid for __________ gases.
ideal
all
very high pressure
very low temperature
ideal
At a given temperature, the volume of a gas dissolved in a solvent __________ with increase in pressure.
increases
decreases
remains unchanged
may increase or decrease; depends on the gas
remains unchanged
Which is an example of closed system ?
Air compressor
Lquid cooling system of an automobile
Boiler
None of these
Lquid cooling system of an automobile
Efficiency of a Carnot engine working between temperatures T1 and T2 (T1 < T) is
A. T2-T1/T2
B. T2-T1/T1
C. T1-T2/T2
D. T1-T2/T1
A. T2-T1/T2
Melting of wax is accompanied with __________ in entropy.
increase
decrease
no change
none of these
increase
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
Work done in case of free expansion is
indeterminate
zero
negative
none of these
zero
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
0
1
∞
none of these
1
During adiabatic expansion of gas
pressure remains constant.
pressure is increased.
temperature remains constant.
none of these.
none of these.
Which of the following has the minimum value of COP for a given refrigeration effect?
Reverse Carnot cycle.
Ordinary vapour-compression cycle.
Vapour-compression process with a reversible expansion engine.
Air refrigeration cycle.
Air refrigeration cycle.
__________ decreases during adiabatic throttling of a perfect gas.
Entropy
Temperature
Enthalpy
Pressure
Pressure
Pick out the wrong statement.
Minimum number of degree of freedom of a system is zero.
Degree of freedom of a system containing a gaseous mixture of helium, carbon dioxide and hydrogen is 4.
For a two phase system in equilibrium made up of four non-reacting chemical species, the number of degrees of freedom is 4.
Enthalpy and internal energy change is zero during phase change processes like melting, vaporisation and sublimation.
Enthalpy and internal energy change is zero during phase change processes like melting, vaporisation and sublimation.
Tea kept in a thermos flask is vigorously shaken. If the tea is considered as a system, then its temperature will
increase
decrease
remain unchanged
first fall and then rise.
increase
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
Clausius - Clayperon equation is applicable to __________ equilibrium processes.
solid-vapor
solid-liquid
liquid-vapor
all (a), (b) and (c)
all (a), (b) and (c)
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
After throttling, gas temperature
decreases
increases
remains same
may increase or decrease ; depends on the nature of the gas
decreases
The chemical potential for a pure substance is __________ its partial molal free energy.
more than
less than
equal to
not related to
equal to
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
same in both the phases.
zero in both the phases.
more in vapour phase.
more in liquid phase.
same in both the phases.
COP of a refrigerator drawing 1 kW of power per ton of refrigeration is about
0.5
3.5
4.5
8.5
3.5
The number of degrees of freedom for a mixture of ice and water (liquid) are
2
3
1
0
1
On opening the door of an operating refrigerator kept in a closed room, the temperature of the room will
increase
decrease
remain same
increase in summer and will decrease in winter
increase
Domestic refrigerator usually works on the __________ refrigeration cycle.
Carnot
air
absorption
vapour-ejection
absorption
Gibbs-Duhem equation:
states that n1dμ1 + n2dμ2 + ….njdμj = 0, for a system of definite composition at constant temperature and pressure.
applies only to binary systems.
finds no application in gas-liquid equilibria involved in distillation.
none of these
states that n1dμ1 + n2dμ2 + ….njdμj = 0, for a system of definite composition at constant temperature and pressure.
Minimum number of phases that exists in a system is 1. Number of chemical species in a colloidal system is
1
4
2
3
2
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
pressure
volume
temperature
all (a), (b) & (c).
temperature
“When a gas is expanded from high pressure region to low pressure region ; temperature change occurs”. This phenomenon is related to the
Gibbs-Duhem equation
Gibbs-Helmholtz equation
Third law of thermodynamics
Joule-Thomson effect
Joule-Thomson effect
The internal energy of an ideal gas does not change in a reversible __________ process.
isothermal
adiabatic
isobaric
isometric
isothermal
A/an __________ system is exemplified by a vessel containing a volatile liquid in contact with its vapor.
isolated
closed
open
none of these
open
In a P-V diagram (for an ideal gas), an isothermal curve will coincide withan adiabatic curve (through a point), when
Cp < Cv
Cp = Cv
Cp > Cv
C ≥ Cv
Cp = Cv
For an ideal gas, the chemical potential is given by
RT dlnP
R dlnP
R dlnf
none of these
RT dlnP
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
same
doubled
halved
one fourth of its original value
same
In the ammonia synthesis reaction, N2 + 3H2 2NH3 + 22.4 kcal, the formation of NH3 will be favoured by
high temperature.
low pressure.
low temperature only.
both low temperature and high pressure.
both low temperature and high pressure.
Entropy change for an irreversible isolated system is
∞
0
< 0
> 0
> 0
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
The Joule-Thomson co-efficient is defined as (∂T/∂P)H. Its value at the inversion point is
∞
1
0
-ve
0
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.
decreases
decreases exponentially
increases
remains constant
increases
Entropy is a/an
state function
macroscopic property
extensive property
none of these
none of these
In the reaction, represented by, 2SO2 + O2 2SO3; ΔH = - 42 kcal; the forward reaction will be favoured by
low temperature
high pressure
both (a) and (b)
neither (a) nor (b)
both (a) and (b)
At triple point (for one component system), vapour pressure of solid as compared to that of liquid will be
more
less
same
more or less ; depending on the system.
same
4 kg moles of an ideal gas expands in vacuum spontaneously. The work done is
4 J
∞
0
8 J
0
Which of the following is not correct for a reversible adiabatic process ?
TV^γ-1 = constant
p^1-γ.T^Y = constant
PV^γ = constant
none of these
none of these
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 ____.
T1/(T1-T2)
T2/(T1-T2)
T1/T2
T2/R1
T1/(T1-T2)
Throttling (Joule-Thomson effect) process is a constant __________ process.
enthalpy
entropy
pressure
none of these
enthalpy
Boiling of liquid is accompanied with increase in the
vapor pressure.
specific Gibbs free energy.
specific entropy.
all (a), (b) and (c).
vapor pressure.
Change of state namely evaportation condensation, freezing and melting is an __________ process.
isothermal
adiabatic
isobaric
isochoric
isothermal
Which of the following is not an equation of state?
Bertholet equation
Clausius Clayperon equation
Beattie-Bridgeman equation
None of these
Clausius Clayperon equation
A gas shows deviation from ideal behaviour at
low pressure and high temperature.
low pressure and low temperature.
low temperature and high pressure.
high temperature and high pressure.
low temperature and high pressure.
The difference between isothermal compressibility and adiabatic compressibility for an ideal gas is
0
+ve
-ve
∞
+ve
The expression for entropy change given by, ΔS = - nR ln (P2/P1), holds good for
expansion of a real gas.
reversible isothermal volume change.
heating of an ideal gas.
cooling of a real gas.
reversible isothermal volume change.
With increase in temperature, the internal energy of a substance
increases
decreases
remains unchanged
may increase or decrease; depends on the substance
increases
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.
For a constant pressure reversible process, the enthalpy change (ΔH) of the system is
Cv.dT
Cp.dT
∫Cp.dT
∫Cv.dT
∫Cp.dT
The work done in isothermal compression compared to that in adiabatic compression will be
less
more
same
more or less depending upon the extent of work done
more
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
When liquid and vapour phases of one component system are in equilibrium (at a given temperature and pressure), the molar free energy is
more in vapour phase.
more in liquid phase.
same in both the phases.
replaced by chemical potential which is more in vapour phase.
same in both the phases.
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
What happens in a reversible adiabatic compression ?
Heating occurs
Cooling occurs
Pressure is constant
Temperature is constant
Heating occurs
Sublimation temperature of dry ice (solid CO2) is __________ °C.
-273
0
-78
5
-78
If atmospheric temperature and dew point are nearly equal, then the relative humidity is
zero
50%
almost 100%
unpredictable
almost 100%
The internal energy of an incompressible fluid depends upon its
pressure
temperature
both (a) & (b)
neither (a) nor (b)
both (a) & (b)
Entropy change in case of reversible adiabatic process is
minimum
zero
maximum
indeterminate
zero
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
more
less
same
unpredictable; depends on the particular reaction
same
For multicomponent multiple phases to be in equilibrium at the same pressure and temperature, the __________ of each component must be same in all phases.
chemical potential
fugacity
both (a) and (b)
neither (a) nor (b)
both (a) and (b)
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
Mollier chart is a __________ plot.
pressure vs enthalpy
pressure vs volume
enthalpy vs entropy
temperature vs entropy
enthalpy vs entropy
Variation of equilibrium pressure with temperature for any two phases of a given substances is given by the __________ equation.
Gibbs-Duhem
Maxwell’s
Clayperon
none of these
Clayperon
Pick out the undesirable property for a good refrigerant.
high thermal conductivity
low freezing point
large latent heat of vaporisation
high viscosity
high viscosity
Isotherm on an enthalpy-concentration diagram, for an ideal solution will be a
straight line
sine curve
parabola
hyperbola
straight line
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
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.
448
224
22.4
data insufficient; can’t be computed
448
Rotary lime kiln is an example of a/an __________ system.
closed
open
isolated
non-thermodynamic
open
Heat of reaction is
dependent on pressure only.
dependent on temperature only.
dependent on both pressure and temperature.
independent of temperature changes.
dependent on both pressure and temperature.
The expression, nRTln(P1/P2), is for the____of an ideal gas.
compressibility
work done under adiabatic contition
work done under isothermal condition
co-efficient of thermal expansion
work done under isothermal condition
What happens in a reversible adiabatic expansion process ?
Heating takes place.
Cooling takes place.
Pressure is constant.
Temperature is constant.
Cooling takes place.
Degree of freedom of a system consisting of a gaseous mixture of H2 and NH3 will be
0
1
2
3
3
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)
(∂P/∂V)S = (∂P/∂V)T
(∂P/∂V)S = [(∂P/∂V)T]Y
(∂P/∂V)S = y(∂P/∂V)T
(∂P/∂V)S = 1/y(∂P/∂V)T
(∂P/∂V)S = y(∂P/∂V)T
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.
Fugacity co-efficient of a substance is the ratio of its fugacity to
mole fraction
activity
pressure
activity co-efficient
pressure
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.
Bomb
Separating
Bucket
Throttling
Bomb
As the time is passing, entropy of the universe
is increasing
is decreasing
remains constant
data insufficient, can’t be predicted
is increasing
Which of the following processes can not be made reversible even under ideal condition of operation?
Free expansion of a gas.
Compression of air in a compressor.
Expansion of steam in a turbine.
all (a), (b) & (c).
Free expansion of a gas.
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.
Gibbs-Duhem
Van Laar
Gibbs-Helmholtz
Margules
Gibbs-Duhem
Which of the following identities can be most easily used to verify steam table data for superheated steam.
(∂T/∂V)S = (∂p/∂S)V
(∂T/∂P)S = (∂V/∂S)P
(∂P/∂T)V = (∂S/∂V)T
(∂V/∂T)P = -(∂S/∂P)T
(∂V/∂T)P = -(∂S/∂P)T
In the equation PVn = constant, if the value of n = y = Cp/Cv, then it represents a reversible __________ process.
isothermal
adiabatic
isentropic
polytropic
isentropic
The ammonia synthesis reaction represented by N2 + 3H2 → 2NH3 ; ΔH = - 22.4 kcal, is
endothermic
exothermic
isothermal
adiabatic
exothermic
With increase in temperature, the atomic heat capacities of all solid elements
increases
decreases
remains unchanged
decreases linearly
increases
The temperature at the eutectic point of the system is the __________ temperature that can be attained in the system.
lowest
highest
average
none of these
lowest
The effect of changing the evaporator temperature on COP as compared to that of changing the condenser temperature (in vapour compression refrigeration system) is
less pronounced
more pronounced
equal
data insufficient, can’t be predicted.
more pronounced
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
superheated vapour.
partially condensed vapour with quality of 0.9.
saturated vapour.
partially condensed vapour with quality of 0.1.
superheated vapour.
An isentropic process is carried out at constant ______.
volume
pressure
temperature
all (a), (b) and (c)
volume
All gases except __________ shows a cooling effect during throttling process at atmospheric temperature and pressure.
oxygen
nitrogen
air
hydrogen
hydrogen
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:
Δ H = 0 and ΔS = 0.
Δ H ≠ 0 and ΔS = 0.
Δ H ≠ 0 and ΔS ≠ 0.
Δ H = 0 and ΔS ≠ 0.
Δ H ≠ 0 and ΔS = 0.
The necessary condition for phase equilibrium in a multiphase system of N components is that the _____.
chemical potentials of a given component should be equal in all phases.
chemical potentials of all components should be same in a particular phase.
sum of the chemical potentials of any given component in all the phases should be the same.
none of these.
chemical potentials of a given component should be equal in all phases.
Compressibility factor-reduced pressure plot on reduced co-ordinates facilitates
use of only one graph for all gases.
covering of wide range.
easier plotting.
more accurate plotting.
use of only one graph for all gases.
Which of the following is not an intensive property ?
Molar heat capacity
Internal energy
Viscosity
None of these
Internal energy
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
Absorption/evolution of heat during conversion of a substance from one allotropic form to another is termed as the heat of
sublimation
fusion
transition
vaporisation
transition
Ideal gas law is applicable at
low T, low P
high T, high P
low T, high P
high T, low P
high T, low P
Reduced pressure of a gas is the ratio of its
pressure to critical pressure.
critical pressure to pressure.
pressure to pseudocritical pressure.
pseudocritical pressure to pressure.
pressure to critical pressure.
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
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
300(3^2/7)
300(3^3/5)
300(33^3/7)
300(3^5/7)
300(3^2/7)
Entropy change for an irreversible process taking system and surrounding together is
0
> 0
< 0
none of these
> 0
In a homogeneous solution, the fugacity of a component depends upon the
pressure
composition
temperature
all (a), (b) and (c)
all (a), (b) and (c)
For an incompressible fluid, the __________ is a function of both pressure as well as temperature.
internal energy
enthalpy
entropy
all (a), (b) & (c)
enthalpy
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
What is the degree of freedom for a system comprising liquid water equilibrium with its vapour ?
0
1
2
3
1
Equilibrium constant of a reaction varies with the
initial concentration of the reactant.
pressure.
temperature.
none of these.
temperature.
Third law of thermodynamics is concerned with the
value of absolute entropy.
energy transfer.
direction of energy transfer.
none of these.
value of absolute entropy.
Claude’s liquefaction process employs the cooling of gases by ____.
expansion in an engine
following a constant pressure cycle
throttling
none of these
expansion in an engine
Gibbs free energy (F) is defined as
F = E - TS
F = H - TS
F = H + TS
F = E + TS
F = H - TS
The expression for entropy change given by, ΔS = nR ln (V2/V1) + nCv ln (T2/T1) is valid for
reversible isothermal volume change.
heating of a substance.
cooling of a substance.
simultaneous heating and expansion of an ideal gas.
simultaneous heating and expansion of an ideal gas.
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.
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.
A refrigerator works on the principle of __________ law of thermodynamics.
zeroth
first
second
third
second
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.
Pick out the wrong statement.
Enthalpies of all elements in their standard states are assumed to be zero.
Combustion reactions are never en-dothermic in nature.
Heat of reaction at constant volume is equal to the change in internal energy.
Claussius-clayperon equation is not applicable to melting process.
Claussius-clayperon equation is not applicable to melting process.
Which of the following is affected by the temperature ?
Fugacity
Activity co-efficient
Free energy
All (a), (b) & (c)
All (a), (b) & (c)
Work done may be calculated by the expression ∫p.dA for __________ processes.
non-flow reversible
adiabatic
both (a) and (b)
neither (a) nor (b)
both (a) and (b)
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 . x2^2
Ax1
Ax2
Ax1^2
A . x2^2
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.
For spontaneous changes in an isolated system (S = entropy)
ds = 0
ds <0
ds > 0
ds = Constant
ds > 0
A gas performs the maximum work, when it expands
non-uniformly
adiabatically
isobarically
isothermally
isobarically
There is a change in __________ during the phase transition.
volume
pressure
temperature
all a, b & c
volume
Pressure-enthalpy chart is useful in refrigeration. The change in internal energy of an ideal fluid used in ideal refrigeration cycle is
positive
negative
zero
infinity
zero
First law of thermodynamics deals with the
direction of energy transfer.
reversible processes only.
irreversible processes only.
none of these.
direction of energy transfer.
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
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
4
3
5
6
3
1m3 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
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.
Standard temperature and pressure (S.T.P.) is
0°C and 750 mm Hg
15°C and 750 mm Hg
0°C and 1 kgf/cm2
15°C and 1 kgf/cm2
0°C and 750 mm Hg
Normal temperature and pressure (N.T.P.) corresponds to
0°C and 760 mm Hg.
15°C and 760 mm Hg.
20°C and 760 mm Hg.
0°C and 1 kgf/cm2.
20°C and 760 mm Hg.
The minimum number of phases that can exist in a system is
0
1
2
3
1
Enthalpy changes over a constant pressure path are always zero for __________ gas.
any
a perfect
an easily liquefiable
a real
a perfect
‘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
__________ does not change during phase transformation processes like sublimation, melting & vaporisation.
Entropy
Gibbs free energy
Internal energy
all (a), (b) & (c)
Gibbs free energy
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.
Choose the condition that must be specified in order to liquify CO2 (triple point for CO2 is - 57°C and 5.2 atm).
Pressure must be kept below 5.2 atm.
Temperature must be kept above - 57°C.
Pressure must be kept below 5.2 atm. and temperature must be kept above 57°C.
Pressure and temperature must be kept below 5.2 atm. and - 57°C respectively.
Pressure and temperature must be kept below 5.2 atm. and - 57°C respectively.
If two pure liquid constituents are mixed in any proportion to give an ideal solution, there is no change in
volume
enthalpy
both (a) & (b)
neither (a) nor (b)
both (a) & (b)
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
Lenz’s law results from the law of conservation of
mass
momentum
energy
none of these
energy
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.
isometric
polytropic
isentropic
isobaric
polytropic
Throttling process is a/an __________ process.
reversible and isothermal
irreversible and constant enthalpy
reversible and constant entropy
reversible and constant enthalpy
irreversible and constant enthalpy
The main feature of Carnot refrigeration cycle is that, it
does not need the addition of external work for its functioning.
transfers heat from high temperature to low temperature.
accomplishes the reverse effect of the heat engine.
none of these.
accomplishes the reverse effect of the heat engine.
Heat of reaction at constant volume is identified with __________ change.
enthalpy
internal energy
either (a) or (b)
neither (a) nor (b)
internal energy
Charles’ law for gases states that
V/T = Constant
V ⍺ 1/T
V ⍺ 1/P
PV/T = Constant
V/T = Constant
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.
-19.4
-30.2
55.2
-55.2
-19.4
Helmholtz free energy (A) is defined as
A = H - TS
A = E - TS
A = H + TS
none of these
A = E - TS
As pressure approaches zero, the ratio of fugacity to pressure (f/P) for a gas approaches
zero
unity
infinity
an indeterminate value
unity
For any system, what is the minimum number of degrees of freedom?
1
0
2
3
0
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
At absolute zero temperature, the __________ of the gas is zero.
pressure
volume
mass
none of these
volume
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, dlogPA/dlogexA = dlogePB/dlogexB, 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
Gases are cooled in Joule-Thomson expansion, when it is __________ inversion temperature.
below
at
above
either ‘b’ or ‘c’
below
PV^y = constant, holds good for an isentropic process, which is
reversible and isothermal.
isothermal and irreversible.
reversible and adiabatic.
adiabatic and irreversible.
reversible and adiabatic.
Which of the following behaves most closely like an ideal gas ?
He
N2
O2
H2
He
In the reaction, C + O2 CO2 ; ΔH = - 94 kcal. What is the heat content (enthalpy)of O2?
-94 kcal
> -94 kcal
< - 94 kcal
zero
zero
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
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, PVn = constant, if the value of n = ± ∞, then it represents a reversible __________ process.
adiabatic
isometric
isentropic
isothermal
isometric
Degree of freedom of the system ice-water-vapour will be
0
1
2
3
0
A system in which there is exchange of energy but not of mass, is called a/an __________ system.
isolated
open
insulated
closed
closed
The point at which all the three (solid, liquid and gas) phases co-exist, is known as the __________ point.
freezing
triple
boiling
Boyle
triple
In an ideal gas mixture, fugacity of a species is equal to its
vapor pressure
partial pressure
chemical potential
none of these
partial pressure
The third law of thermodynamics states that the
heat capacity of a crystalline solid is zero at absolute zero temperature.
heat transfer from low temperature to high temperature source is not possible without external work.
gases having same reduced properties behave similarly.
none of these.
heat capacity of a crystalline solid is zero at absolute zero temperature.
Consider the reaction, C + O2 CO2 ;ΔH = - 94 kcal. What will be the value of ΔH for the reaction CO2 C + O2 ?
-94 kcal
+ 94 kcal
> 94 kcal
< -94 kcal
+ 94 kcal
Which is not a state function ?
Specific volume
Work
Pressure
Temperature
Work
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
To obtain integrated form of Clausius-Clayperon equation, , from the exact Clayperon equafion, it is assumed that the
volume of the liquid phase is negligible compared to that of vapour phase.
vapour phase behaves as an ideal gas.
heat of vaporisation is independent of temperature.
all (a), (b) & (c).
all (a), (b) & (c).
In case of an __________ process, the temperature of the system increases.
isothermal compression
isothermal expansion
adiabatic expansion
adiabatic compression
adiabatic compression
The standard state of a gas (at a given temperature) is the state in which fugacity is equal to
unity
activity
both (a) & (b)
neither (a) nor (b)
both (a) & (b)
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 zero.
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).
For an ideal gas, the internal energy depends upon its __________ only.
molecular size
temperature
volume
pressure
temperature
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.
Second law of thermodynamics is concerned with the
amount of energy transferred.
direction of energy transfer.
irreversible processes only.
non-cyclic processes only.
direction of energy transfer.
