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)

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

4

Isothermal

Isentropic

None of these

4

0.15

1.5

4.5

6.5

4

# Third law of thermodynamics is helpful in

Prediction of the extent of a chemical reaction

Calculating absolute entropies of substances at different temperature

Evaluating entropy changes of chemical reaction

Both (B) and (C)

4

# Pick out the wrong statement.

Activity co-efficient is dimensionless.

In case of an ideal gas, the fugacity 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

4

# Which of the following decreases with increase in pressure?

Melting point of ice

Melting point of wax

Boiling point of liquids

None of these

4

-2 RT ln 0.5

-RT ln 0.5

0.5 RT

2 RT

4

# 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

4

# 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

4

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

Positive

Negative

Zero

May be positive or negative

4

-ve

0

+ve

4

Ideal

Real

Isotonic

None of these

4

# Work done is a

Property of the system

Path function

Point function

State description of a system

4

# Pick out the wrong statement.

The chemical potential of a pure substance depends upon the temperature and pressure

The chemical potential of a component in a system is directly proportional to the escaping tendency of that component

The chemical potential of ith species (μi) in an ideal gas mixture approaches zero as the pressure or mole fraction (xi) tends to be zero at constant temperature

The chemical potential of species 'i' in the mixture (μi) is mathematically represented as,μi = ∂(nG)/∂ni]T,P,nj where, n, ni and nj respectively denote the total number of moles, moles of ith species and all mole numbers except ith species. 'G' is Gibbs molar free energy

4

Free energy

Entropy

Refractive index

None of these

4

# In vapour compression refrigeration system, if the evaporator temperature and the condenser temperatures are -13°C and 37°C respectively, the Carnot COP will be

5.2

6.2

0.168

Data insufficient, can't be found out

4

3

4

5

6

4

Zero

Unity

Infinity

None of these

4

dE = CpdT

dE = CvdT

dQ = dE + pdV

dW = pdV

4

Gibbs-Duhem

Van Laar

Gibbs-Helmholtz

Margules

4

# 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

4

Increase

Decrease

Not alter

None of these

4

Isothermal

Isobaric

Isochoric

4

Critical

Boyle

Inversion

Reduced

4

0

50

100

4

1st

Zeroth

3rd

None of these

4

< 0

> 0

= 0

None of these

4

# A Carnot cycle consists of the following steps:

Two isothermal and two isentropic

Two isobaric and two isothermal

Two isochoric and two isobaric

Two isothermals and two isochoric

4

Carnot

Air

Absorption

vapour-ejection

4

# 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

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