A gas at $800^{\circ} \mathrm{C}$ is cooled until both its pressure and volume are halved. The final temperature of the gas will be

When the r.m.s. velocity of a gas is denoted by ' V ' and temperature of the gas by T , which of the following relations is TRUE?

The average kinetic energy of a molecule of the gas is

Two spherical black bodies of radius $\mathrm{R}_1$ and $\mathrm{R}_2$ with surface temperatures $\mathrm{T}_1$ and $\mathrm{T}_2$ respectively. If $T_1=2 T_2$ and they radiate the same power then relation between $R_1$ and $R_2$ is