If the door of a refrigerator is kept open in an insulated room,the temperature of the air in the room will . . . . . .

Obtain the formula for the coefficient of performance of a Carnot refrigerator.

$A$ Carnot engine,having an efficiency of $\eta = 1/10$ 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 ....... $J$.

If the door of a refrigerator is kept open,then which of the following is true?

In a cold storage,ice melts at the rate of $2 \ kg$ per hour when the external temperature is $20^{\circ} C$. The minimum power output of the motor used to drive the refrigerator which just prevents the ice from melting is (latent heat of fusion of ice $= 80 \ cal \ g^{-1}$) (in $W$)

If $\alpha$ is the coefficient of performance of a refrigerator and $Q_1$ is the heat released to the hot reservoir,then the heat extracted from the cold reservoir $Q_2$ is