The work done in which of the following processes is equal to the internal energy of the system?

An ideal gas undergoes an adiabatic process from state $(P_1, V_1, T_1)$ to $(P_2, V_2, T_2)$. The work done during the process is ..... (where $\mu$ = number of moles,$C_P$ and $C_V$ = molar specific heats).

The relation between volume $(V)$ and absolute temperature $(T)$ of a gas in an adiabatic process is

$A$ sample of gas at temperature $T$ is adiabatically expanded to double its volume. The adiabatic constant for the gas is $\gamma = 3/2$. The work done by the gas in the process is: $(\mu = 1 \text{ mole})$

$A$ monoatomic gas having $\gamma = 5/3$ is stored in a thermally insulated container and the gas is suddenly compressed to $(1/8)^{th}$ of its initial volume. The ratio of final pressure to initial pressure is: ($\gamma$ is the ratio of specific heats of the gas at constant pressure and at constant volume).

$A$ rigid diatomic gas undergoes adiabatic change. Its pressure $P$ and temperature $T$ are related as $P \propto T^x$ where $x$ is (in $.5$)