If a gas is compressed isothermally then the r.m.s. velocity of its molecules

In a cyclic process, work done by the system is

A metal sphere cools at a rate of $1.5^{\circ} \mathrm{C} / \mathrm{min}$ when its temperature is $80^{\circ} \mathrm{C}$. When the temperature of the sphere is $40^{\circ} \mathrm{C}$, its rate of cooling is $0.3^{\circ} \mathrm{C} / \mathrm{min}$. The temperature of the surrounding $\left(\theta_0\right)$ is