A monoatomic gas at pressure $P$ and volume $V$ is suddenly compressed to one eighth of its original volume. The final pressure at constant entropy will be $.....P$

Consider a spherical shell of radius $R$ at temperature $T$. The black body radiation inside it can be considered as an ideal gas of photons with internal energy per unit volume$E=$ $\frac{U}{V} \propto {T^4}$ and pressure $P = \frac{1}{3}\left( {\frac{U}{V}} \right)$ If the shell now undergoes an adiabatic expansion the relation between $T$ and $R$ is

The process in which no heat enters or leaves the system is termed as

Four curves $A, B, C$ and $D$ are drawn in the adjoining figure for a given amount of gas. The curves which represent adiabatic and isothermal changes are

The adiabatic elasticity of hydrogen gas $(\gamma = 1.4)$ at $NTP$ is

$Assertion :$ Adiabatic expansion is always accompanied by fall in temperature.
$Reason :$ In adiabatic process, volume is inversely proportional to temperature.