A body cools from a temperature of $60^{\circ} \mathrm{C}$ to $50^{\circ} \mathrm{C}$ in 10 minutes and $50^{\circ} \mathrm{C}$ to $40^{\circ} \mathrm{C}$ in 15 minutes. The time taken in minutes for the body to cool from $40^{\circ} \mathrm{C}$ to $30^{\circ} \mathrm{C}$ is

When the temperature of a gas in a closed vessel is increased by $2.4^{\circ} \mathrm{C}$, its pressure increases by $0.5 \%$. The initial temperature of the gas is

A gas is suddenly compressed such that its absolute temperature is doubled. If the ratio of the specific heat capacities of the gas is 1.5 , then the percentage decrease in the volume of the gas is

If the heat required to increase the rms speed of 4 moles of a diatomic gas from $v$ to $\sqrt{3} v$ is 83.1 kJ , then the initial temperature of the gas is

(universal gas constant $=8.31 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$ )