Which graph represents the variation of $PV$ with $V$ for a fixed mass of an ideal gas at constant temperature?

Two thermally insulated vessels $1$ and $2$ contain air at temperatures $(T_1, T_2)$,volumes $(V_1, V_2)$,and pressures $(P_1, P_2)$. If the valve connecting them is opened,what will be the equilibrium temperature of the system?

If a closed container containing gas is in motion and is suddenly stopped,the random motion of the gas molecules will .......

According to the kinetic theory of gases,when two molecules of a gas collide with each other,then:

Fill in the blanks:
$(i)$ At absolute zero,the volume of an ideal gas is ...... .
$(ii)$ With an increase in temperature,the pressure of a gas ...... .
$(iii)$ All molecular motion will stop at ...... .
$(iv)$ Due to ...... at higher altitudes from the surface of the Earth,the air becomes cooler.

One mole of an ideal gas at standard temperature and pressure occupies $22.4 \; L$ (molar volume). What is the ratio of molar volume to the atomic volume of a mole of hydrogen? (Take the size of a hydrogen molecule to be about $1 \; \mathring{A}$). Why is this ratio so large?