4

Isothermal

Isentropic

Isobaric

4

# 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 eccentric factor for all materials is always more than one

4

# 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

4

# Gibbs free energy per mole for a pure substance is equal to the

Latent heat of vaporisation

Chemical potential

Molal boiling point

Heat capacity

4

# 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)

4

-94 kcal

+94 kcal

> 94 kcal

< -94 kcal

4

# A refrigeration cycle is the same as a __________ cycle,

Turbine

Heat engine

Reversed heat engine

None of these

4

Zero

Positive

Negative

Indeterminate

4

# Throttling process is a/an __________ process.

Reversible and isothermal

Irreversible and constant enthalpy

Reversible and constant entropy

Reversible and constant enthalpy

4

# Specific __________ does not change during a phase change (e.g. sublimation, melting, vaporisation etc.).

Entropy

Internal energy

Enthalpy

Gibbs free energy

4

RT d ln P

R d ln P

R d ln f

None of these

4

# 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'

4

Isothermal

Isobaric

Polytropic

4

# 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)

4

Isothermal

Isobaric

Isometric

4

Rectangle

Rhombus

Trapezoid

Circle

4

No

Any real

Only ideal

Both (B) and (C)

4

# For an exothermic reaction

Only enthalpy change (ΔH) is negative

Only internal energy change (ΔE) is negative

Both ΔH and ΔE are negative

Enthalpy change is zero

4

# The change in Gibbs free energy for vaporisation of a pure substance is

Positive

Negative

Zero

May be positive or negative

4

# Refrigerants commonly used for domestic refrigerators are

Ethyl chloride or methyl chloride

Freon-12

Propane

NH3 or CO2

4

Logarithmic

Arithmetic

Geometric

Harmonic

4

Concentration

Mass

Temperature

Entropy

4

Mass

Momentum

Energy

None of these

4

# 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

4

# 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

4

Zero

Positive

Negative

None of these

4

# 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)

4

(∂E/∂T)V

(∂E/∂V)T

(∂E/∂P)V

(∂V/∂T)P

4

# Pick out the wrong statement.

Enthalpies of all elements in their standard states are assumed to be zero

Combustion reactions are never endothermic in nature

Heat of reaction at constant volume is equal to the change in internal energy

Clausius-Clapeyron equation is not applicable to melting process

4

Isothermal

Isentropic

None of these