4

# High pressure steam is expanded adiabatically 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

B. Δ H ≠ 0 and ΔS = 0

4

Reversible

Isothermal

None of these

4

# Adiabatic compression of a saturated water vapour makes it

Supersaturated

Superheated

Both (A) and (B)

Neither (A) nor (B)

4

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

(∂E/∂ni)S, v, nj

(∂G/∂ni)T, P, nj = (∂A/∂ni) T, v, nj

(∂H/∂ni)S, P, nj

All (A), (B) and (C)

4

Zeroth

First

Second

Third

4

Indeterminate

Zero

Negative

None of these

4

Free energy

Entropy

Refractive index

None of these

4

# Water on heating from 1 to 4°C

Contracts

Expands

Has same volume

May contract or expand

4

First law

Zeroth law

Third law

Second law

4

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

Entropy

Internal energy

Enthalpy

Gibbs free energy

4

# When pressure is applied on the system, ice ↔ water, then

Equilibrium cannot be established

More ice will be formed

More water will be formed

Evaporation of water will take place

4

# 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

4

# Equilibrium constant of a reaction varies with the

Initial concentration of the reactant

Pressure

Temperature

None of these

4

# Heat pump

Accomplishes only space heating in winter

Accomplishes only space cooling in summer

Accomplishes both (A) and (B)

Works on Carnot cycle

4

# With increase in compression ratio, the efficiency of the otto engine

Increases

Decreases

Remain constant

Increases linearly

4

# 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 cannot be exchanged

All the natural processes are reversible in nature

Work is a state function

4

# 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

4

Isolated

Closed

Open

None of these

4

# 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

4

# Pick out the wrong statement.

The values of (∂P/∂V)T and (∂2P/∂V2)T are zero for a real gas at its critical point

Heat transferred is equal to the change in the enthalpy of the system, for a constant pressure, non-flow, mechanically reversible process

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

During a reversible adiabatic process, the entropy of a substance remains constant

4

# __________ does not change during phase transformation processes like sublimation, melting & vaporisation.

Entropy

Gibbs free energy

Internal energy

All (A), (B) & (C)

4

# 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

4

# Pick out the wrong statement.

A refrigeration cycle violates the second law of thermodynamics

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

4

# 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

4

# Out of the following refrigeration 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

4

Temperature

Mass

Volume

Pressure

4

0

1

2

3

4

# (∂H/∂T)P is the mathematical expression for

CV

Entropy change

Gibbs free energy

None of these

4

Freon-12

Ethylene

Ammonia

Carbon dioxide

4

# 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