### Thermodynamics (Second Law of Thermodynamics)

1.         Second law of thermodynamics defines
(a) heat
(b) work
(c) enthalpy
(d) entropy
(e) internal energy.

2.         For a reversible adiabatic process, the change in entropy is
(a) zero
(b) minimum
(c) maximum
(d) infinite
(e) unity.

3.         For any reversible process, the change in entropy of the system and surroundings is
(a) zero
(b) unity
(c) negative
(d) positive
(e) infinite.

4.         For any irreversible process the net entropy change is
(a) zero
(b) positive
(c) negative
(d) infinite
(e) unity.

5.         The processes of a Carnot cycle are
(a) two adiabatic and two constant volume
(b) one constant volume and one constant pressure and two isentropics
(c) two adiabatics and two isothermals (d) two constant volumes and two isothermals
(e) two isothermals and two isentropics.

6.         Isentropic flow is
(b) ideal fluid flow
(c) perfect gas flow
(d) frictionless reversible flow

7.         In a Carnot engine, when the working substance gives heat to the sink
(a) the temperature of the sink increases
(b) the temperature of the sink remains the same
(c) the temperature of the source decreases
(d) the temperatures of both the sink and the source decrease
(e) changes depend on the operating conditions.

8.         If the temperature of the source is increased, the efficiency of the Carnot engine
(a) decreases
(b) increases
(c) does not change
(d) will be equal to the efficiency of a practical engine
(e) depends on other factors.

9.         The efficiency of an ideal Carnot engine depends on
(a) working substance (b) on the temperature of the source only
(c) on the temperature of the sink only
(d) on the temperatures of both the source and the sink
(e) on the construction of engine.

10.       In a reversible cycle, the entropy of the system
(a) increases
(b) decreases
(c) does not change
(d) first increases and then decreases
(e) depends on the properties of working substance.

11.       A frictionless heat engine can be 100% efficient only if its exhaust temperature is
(a) equal to its input temperature
(b) less than its input temperature
(c) 0°C
(d) 0°K
(e) – 100°C.

12.       Kelvin-Planck’s law deals with
(a) conservation of energy
(b) conservation of heat
(c) conservation of mass
(d) conversion of heat into work
(e) conversion of work into heat.

13.       Which of the following statements is correct according to Clausius statement of second law of thermodynamics ?
(a) It is impossible to transfer heat from a body at a lower temperature to a body at a higher temperature
(b) It is impossible to transfer heat from a body at a lower temperature to a body at a higher temperature, without the aid of an external source.
(c) It is possible to transfer heat from a body at a lower temperature to a body at a higher temperature by using refrigeration cycle
(d) None of the above.

1. (d)
2. (a)
3. (a)
4. (b)
5. (e)
6. (e)
7. (b)
8. (b)
9. (d)
10. (c)
11. (d)
12. (d)
13. (b)