Question

An ideal refrigerator has a freezer at a temperature of $-{13}^{\circ }C$ The coefficient of performance of the engine is 5. The temperature of the air (to which heat is rejected) will be

• A. 325°C
• B. 325K
• C. 39°C
• D. 320°C

Answer 1

The correct option is C 39°C

Coeffecient of performance
$K=\frac{T_2}{T_1-T_2}\Rightarrow 5=\frac{(273-13)}{T_1-(273-13)}=\frac{260}{T_1-260}$
$\Rightarrow 5T_1-1300=260\Rightarrow 5T_1=1560$
$\Rightarrow T_1=312K\to {39}^{\circ }C$