A monoatomic ideal gas, initially at temperature ${T_1},$ is enclosed in a cylinder fitted with a frictionless piston. The gas is allowed to expand adiabatically to a temperature. ${T_2}$ by releasing the piston suddenly. If ${L_1}$ and ${L_2}$ are the lengths of the gas column before and after expansion respectively, then ${T_1}/{T_2}$ is given by

Monoatomic, diatomic and triatomic gases whose initial volume and pressure are same, are compressed till their volume becomes half the initial volume.

A gas ($\gamma = 1.3)$ is enclosed in an insulated vessel fitted with insulating piston at a pressure of ${10^5}\,N/{m^2}$. On suddenly pressing the piston the volume is reduced to half the initial volume. The final pressure of the gas is

An engine takes in $5$ moles of air at $20\,^{\circ} C$ and $1$ $atm,$ and compresses it adiabaticaly to $1 / 10^{\text {th }}$ of the original volume. Assuming air to be a diatomic ideal gas made up of rigid molecules, the change in its internal energy during this process comes out to be $X\, kJ$. The value of $X$ to the nearest integer is

$Assertion :$ In adiabatic compression, the internal energy and temperature of the system get decreased.
$Reason :$ The adiabatic compression is a slow process.