A monoatomic ideal gas, initially at temperature $\mathrm{T}_1$ is enclosed in a cylinder fitted with massless, frictionless piston. By releasing the piston suddenly, the gas is allowed to expand adiabatically to a temperature $\mathrm{T}_2$. If $\mathrm{L}_1$ and $\mathrm{L}_2$ are the lengths of the gas columns before and after expansion respectively, then $\left(T_2 / T_1\right)$ is given by

Two bodies A and B at temperatures ' $\mathrm{T}_1$ ' K and ' $\mathrm{T}_2$ ' K respectively have the same dimensions. Their emissivities are in the ratio $16: 1$. At $\mathrm{T}_1=\mathrm{xT}_2$, they radiate the same amount of heat per unit area per unit time. The value of $x$ is

In an isobaric process of an ideal gas, the ratio of heat supplied and work done by the system $\left(\frac{\mathrm{Q}}{\mathrm{W}}\right)$ is $\left[\frac{\mathrm{C}_{\mathrm{P}}}{\mathrm{C}_{\mathrm{V}}}=\gamma\right]$.

The temperature of a body on Kelvin scale is ' $x$ ' $K$. When it is measured by a Fahrenheit thermometer, it is found to be ' x ' ${ }^{\circ} \mathrm{F}$. The value of ' $x$ ' is (nearly)