If the sink and source temperatures of a refrigerator are $4^{\circ} C$ and $15^{\circ} C$ respectively,then the efficiency of the refrigerator is:

The temperature of the freezer compartment of an ideal refrigerator is $-13 \, ^\circ C$. If the coefficient of performance of the refrigerator is $5$,then the temperature of the surroundings (to which heat is rejected) is:

$A$ refrigerator of coefficient of performance $5$ that extracts heat from the cooling compartment at the rate of $250 \ J$ per cycle is placed in a room. The heat released per cycle to the room by the refrigerator is (in $J$)

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

In a refrigerator,heat is removed from a low-temperature reservoir and deposited at a high-temperature reservoir. This requires mechanical work,which is provided by an electric motor. If the motor power is $1 \ kW$ and heat is transferred from $-3^{\circ} C$ to $27^{\circ} C$,calculate the heat removed from the refrigerator per second,assuming the efficiency is $50\%$ of the ideal Carnot refrigerator. (in $kJ/s$)

If the door of a refrigerator is kept open in a room,will it make the room warm or cool?