A vessel of volume $27 \times 10^4 \mathrm{cc}$, contains a mixture of Hydrogen (molar mass $=2 \mathrm{~g} \mathrm{~mol}^{-1}$ ) and oxygen (molar mass $=32 \mathrm{~g} \mathrm{~mol}^{-1}$ ) gas at standard temperature and pressure. If the mass of hydrogen is 16 g , find the mass of oxygen gas contained in the vessel.

Find the mass of oxygen gas with which $1.882 \times 10^{23}$ degrees of freedom are associated at N.T.P. Given: Molar mass of diatomic gas, oxygen is $32 \mathrm{~g} \mathrm{~mol}^{-1}$ and oxygen molecule possess three translational and two rotational degrees of freedom.

Two bodies of specific heats $C_1$ and $C_2$, having the same heat capacities are combined to form a single composite body. The specific heat capacity of the composite body is

1 kg of water at $100^{\circ} \mathrm{C}$ is converted to steam at the same temperature. Volume of 1 cc of water changes to $1671 \times 10^3 \mathrm{cc}$ on boiling. The change in internal energy of the system is (Latent Heat of vaporisation of water is $22.68 \times 10^5 \mathrm{~J} \mathrm{~kg}^{-1} ; 1 \mathrm{~atm}=1.0 \times 10^5 \mathrm{~Pa}$ )