Mark the correct statement regarding entropy.

1.	At 0°C, the entropy of a perfectly crystalline substance is taken to be zero.
2.	At absolute zero temperature, the entropy of a perfectly crystalline substance is positive.
3.	At absolute zero temperature, the entropy of all crystalline substances is taken to be zero.
4.	At absolute zero temperature, the entropy of a perfectly crystalline substance is taken to be zero.

An engine operating between 150°C and 25°C takes 500 J heat from a higher temperature reservoir if there are no frictional losses, then work done by engine is [MH CET 1999]

(1) 147.7 J

(2) 157.75 J

(3) 165.85 J

(4) 169.95 J

The standard entropies of CO₂(g), C(s) and O₂(g) are 213.5, 5.690 and 205 JK^–1 respectively. The standard entropy of formation of CO₂(g) is

(1) 1.86 JK^–1

(2) 1.96 JK^–1

(3) 2.81 JK^–1

(4) 2.86 JK^–1

Equal volumes of monoatomic and diatomic gases at same initial temperature and pressure are mixed. The ratio of specific heats of the mixture (C_p/C_v) will be [AFMC 2002]

(1) 1

(2) 2

(3) 1.67

(4) 1.5

The unit of entropy is -

1. J mol^–1

2. JK mol^–1

3. J mol^–1 K^–1

4. J^–1 K^–1 mol^–1

The entropy changed involved in the conversion of 1 mole of liquid water at 373 K to vapour at the same temperature will be $[\Delta H_{\text{vap}}=2.257kJ/gm]$ [MP PET 2002]

(1) 0.119 kJ

(2) 0.109 kJ

(3) 0.129 kJ

(4) 0.120 kJ

When a liquid boils, there is [JIPMER 2002]

(1) An increase in entropy

(2) A decrease in entropy

(3) An increase in heat of vaporization

(4) An increase in free energy

The work done to contract a gas in a cylinder, is 462 joules. 128 joule energy is evolved in the process. What will be the internal energy change in the process [MP PMT 2003]

(1) + 590 joules

(2) – 334 joules

(3) + 334 joules

(4) – 590 joules

For a carnot engine, the source is at 500 K and the sink at 300 K. What is efficiency of this engine

(1) 0.2

(2) 0.4

(3) 0.6

(4) 0.3

From Kirchhoff's equation which factor affects the heat of reaction [MP PMT 1990]

1. Pressure

2. Temperature

3. Volume

4. Molecularity