Thermodynamics (Physics)

The efficiency of an ideal heat engine working between the freezing point and boiling point of water, is

1. 26.8%
2. 20%
3. 6.25%
4. 12.5%

Thermodynamic processes are indicated in the following diagram. [figure] Match the following

1. (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)
2. (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)
3. (a)-(iv), (b)-(ii), (c)-(i), (d)-(iii)
4. (a)-(i), (b)-(iii), (c)-(iv), (d)-(ii)

A Carnot engine having an efficiency of 110 as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is

1. 90 J
2. 99 J
3. 100 J
4. 1 J

A gas is compressed isothermally to half its initial volume. The same gas is compressed separately through an adiabatic process until its volume is again reduced to half. Then

1. Compressing the gas isothermally or adiabatically will require the same amount of work.
2. Which of the case (whether compression through isothermal or through adiabatic process) requires more work will depend upon the atomicity of the gas.
3. Compressing the gas isothermally will require more work to be done.
4. Compressing the gas through adiabatic process will require more work to be done.

A refrigerator works between 4 and 30 . It is required to remove 600 calories of heat every second in order to keep the temperature of the refrigerated space constant. The power required is (Take 1 cal = 4.2 Joules)

1. 236.5 W
2. 2365 W
3. 2.365 W
4. 23.65 W

One mole of an ideal monatomic gas undergoes a process described by the equation PV3 = constant. The heat capacity of the gas during this process is

1. 32 R
2. 52 R
3. 2R
4. R

The temperature inside a refrigerator is t2 C and the room temperature is t1 C. The amount of heat delivered to the room for each joule of electrical energy consumed ideally will be

1. t1t1 - t2
2. t1 + 273t1 - t2
3. t2 + 273t1 - t2
4. t1 + t2t1 + 273

An ideal gas is compressed to half its initial volume by means of several processes. Which of the process results in the maximum work done on the gas ?

1. Isochoric
2. Isothermal
3. Adiabatic
4. Isobaric

The coefficient of performance of a refrigerator is 5. If the temperature inside freezer is -20 C, the temperature of the surroundings to which it rejects heat is

1. 11 C
2. 21 C
3. 31 C
4. 41 C

A Carnot engine, having an efficiency of = 110 as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is

1. 90 J
2. 1 J
3. 100 J
4. 99 J