Two ideal gases $X$ and $Y$ are kept at the same temperature. The gas $X$ has molar mass ${\mu }_x$ and gas $Y$ has molar mass ${\mu }_y$. What is the ratio of average speeds of the molecules of gas $X$ to that of gas $Y$? 

In an experiment, a heater of power $35 W$ is used to warm $0.240 kg$ of a liquid in an uninsulated container. The graph shows the variation of the temperature of the liquid with time.

The liquid never reaches its boiling point. Suggest why the temperature of the liquid approaches a constant value.

The volume of air in a car tyre is about $1.50\times {10}^{-2} m^3$ at a temperature of $0.0 °C$ and  pressure $250 kPa$.

Calculate the number of molecules in the tyre( in no. of Molecules).