Distinguish between ideal gas and real gas.

$22.4$ litres of gas weighs $70 \mathrm{g}$ at STP. Calculate the weight of the gas if it occupies volume of $20$ litre at ${27}^{\mathrm{o}}\mathrm{C}$ and $700 \mathrm{mm} \mathrm{Hg}$ of pressure. ($\mathrm{R}=62.363 \mathrm{mm} \mathrm{Hg} \mathrm{L} {\mathrm{mol}}^{-1} {\mathrm{K}}^{-1}$)

The molecular theory accounts for the pressure exerted by a gas in a closed vessel as a result of the gas molecules striking against the walls of the vessel.

How will the pressure change if the temperature is doubled keeping the volume constant?

Pressure of $1 \mathrm{g}$ of an ideal gas A at ${27}^{\mathrm{o}} \mathrm{C}$ is found to be $2$ bar. When $2 \mathrm{g}$ of another ideal gas B is introduced in the same flask at same temperature the pressure becomes $3 \mathrm{bar}$. Find a relationship between their molecular masses.