A carnot engine having an efficiency of $\frac{1}{10}$th of heat engine, is used as a refrigerator. If then work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is:

1. 1 J

2. 90 J

3. 99 J

4. 100 J 

A refrigerator works between 4°C and 30°C. 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. 23.65 W

2. 236.5 W

3. 2365 W

4. 2.365 W

The temperature inside a refrigerator (reversible process) is t₂^oC and the room temperature is t₁^oC. The amount of heat delivered to the room for each joule of electrical energy consumed, ideally, will be:

1.  $\frac{t_1}{t_1-t_2}$

2.  $\frac{t_1+273}{t_1-t_2}$

3.  $\frac{t_2+273}{t_1+t_2}$

4.  $\frac{t_1+t_2}{t_1+273}$

A Carnot engine having an efficiency of $\frac{1}{10}$ 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 a lower temperature is:
1. $90$ J
2. $99$ J
3. $100$ J
4. $1$ J

The coefficient of performance of a refrigerator is $5.$ If the temperature inside the freezer is $-20^\circ \text{C},$ the temperature of the surroundings to which it rejects heat is:
1. $31^\circ \text{C}$
2. $41^\circ \text{C}$
3. $11^\circ \text{C}$
4. $21^\circ \text{C}$

A Carnot engine, having an efficiency of $\mathrm{\eta }$ = $\frac{1}{10}$ as a 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 a lower temperature is:
1. $100$ J
2. $99$ J
3. $90$ J
4. $1$ J

An engine has an efficiency of $\frac{1}{6}$. When the temperature of the sink is reduced by ${62}^{0}C$, its efficiency is doubled. the temperature of the source is:

1. 124^oC

2. 37^oC

3. 62^oC

4. 99^oC

An ideal refrigerator has a freezer at a temperature of –13°C . The coefficient of performance of the engine is 5. The temperature of the air (at which heat is rejected) will be 
1. 325°C
2. 325K
3. 39°C
4. 320°C

The coefficient of performance of an ideal refrigerator is 3 which extracts heat from the sink at the rate of 399 J per cycle. The amount of heat it gives to the room per cycle will be:

1 532 J

2 250 J

3 300 J

4 496 J