Pick out the correct statement.
Like internal energy and enthalpy, 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
Correct Answer :
D. Maximum work is done under reversible conditions
Related Questions
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
The internal energy of an incompressible fluid depends upon its
Pressure
Temperature
Both (A) & (B)
Neither (A) nor (B)
Which of the following is Clausius-Clapeyron Equation for vaporisation of an ideal gas under the condition that the molar volume of liquid is negligible compared to that of the vapor?
d ln p/dt = Hvap/RT2
d ln p/dt = RT2/Hvap
dp/dt = RT2/Hvap
dp/dt = Hvap/RT2
For an ideal solution, the value of activity co-efficient is
0
1
< 1
> 1
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
Change of state namely evaporation condensation, freezing and melting is an __________ process.
Isothermal
Adiabatic
Isobaric
Isochoric
For a given substance at a specified temperature, activity is __________ to fugacity.
Directly proportional
Inversely proportional
Equal
None of these
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)
The most important application of distribution law is in
Evaporation
Liquid extraction
Drying
Distillation
Mollier chart is a __________ plot.
Pressure vs. enthalpy
Pressure vs. volume
Enthalpy vs. entropy
Temperature vs. entropy
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?
[∂(G/T)/∂T] = - (H/T2)
[∂(A/T)/∂T]V = - E/T2
Both (A) and (B)
Neither (A) nor (B)
For equilibrium process (i.e. reversible) in an isolated system
ds = 0
ds < 0
ds > 0
ds = Constant
For a single component two phase mixture, the number of independent variable properties are
Two
One
Zero
Three
Which of the following represents the Virial equation of state?
T = [RT/(V- b)] - [a/√T. V(V + b)]
PV/RT = 1 + (B/V) + (C/V2) + ……
n1u2 + μ2μ1 = 0
None of these
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
In a working refrigerator, the value of COP is always
0
< 0
< 1
> 1
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
The expression, ΔG = nRT. ln(P2/P1), gives the free energy change
With pressure changes at constant temperature
Under reversible isothermal volume change
During heating of an ideal gas
During cooling of an ideal gas
A solid is transformed into vapour without going to the liquid phase at
Triple point
Boiling point
Below triple point
Always
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
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
The theoretical minimum work required to separate one mole of a liquid mixture at 1 atm, containing 50 mole % each of n- heptane and noctane into pure compounds each at 1 atm is
-2 RT ln 0.5
-RT ln 0.5
0.5 RT
2 RT
The gas law (PV = RT) is true for an __________ change.
Isothermal
Adiabatic
Both (A) & (B)
Neither (A) nor (B)
Dry ice is
Moisture free ice
Solid helium
Solid carbon dioxide
None of these
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'
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
In the equation, PVn = constant, if the value of n = 1, then it represents a reversible __________ process.
Isothermal
Isobaric
Polytropic
Adiabatic
The unity of Planck's constant 'h' in the equation, E = hv is
J/s
J.S
J/kmol
kmol/J
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
Specific volume of an ideal gas is
Equal to its density
The reciprocal of its density
Proportional to pressure
None of these