A refrigerator whose coefficient of performance is 5 extracts heat from the cooling chamber at a rate of 250 J per cycle. For refrigeration, the work done per cycle is:

1. 150 J

2. 200 J

3. 100 J

4. 50 J

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

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 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.  $\frac{t_1+t_2}{t_1+273}$

If a refrigerator extracts heat 'a' from the cold reservoir and 'b' is the heat released from the hot reservoir, then the work done on the refrigerant (system) is:

1. a + b

2. $\mathrm{a}-\mathrm{b}$

3. a

4. $\mathrm{b}-\mathrm{a}$