If sink and source temperature of a refrigerator are $4^{\circ} C$ and $15^{\circ} C$ respectively. Then efficiency of refrigerator is

An ideal monoatomic gas is taken round the cycle $ABCDA$ as shown in following $P-V$ diagram. The work done during the cycle is

Two cylinders $A$ and $B$ fitted with pistons contain equal amounts of an ideal diatomic gas at $300\,K$ . the position of $A$ is free to move while that of $B$ is held fixed. The same amount of heat is given to the gas in each cylinder. If the rise in temperature of the gas in $A$ is $30\,K$ , then the rise in temperature of the gas in $B$ is   .... $K$

A monoatomic gas $(\gamma = 5/3)$ is suddenly compressed to $\frac{1}{8}$ of its original volume adiabatically, then the pressure of the gas will change to

$1\, mole$ of an ideal gas at temperature $T_1$ expands according to the law $(P/V) =$ constant. Find the work done when the final temperature becomes $T_2$

The ratio of the specific heats $\frac{{{C_p}}}{{{C_V}}} = \gamma $ in terms of degrees of freedom $(n)$ is givln by