The graph shows the $PV$ vs $P$ plot for different gases at a constant temperature. Which graph represents an ideal gas?

The change in the magnitude of the volume of an ideal gas when a small additional pressure $\Delta P$ is applied at a constant temperature is the same as the change when the temperature is reduced by a small quantity $\Delta T$ at constant pressure. The initial temperature and pressure of the gas were $300 \ K$ and $2 \ atm$ respectively. If $|\Delta T| = C|\Delta P|$,then the value of $C$ in $(K/atm)$ is......

In the figure,the volume of container $X$ is twice the volume of container $Y$. Both contain an ideal gas. The temperature of $X$ is $200 \, K$ and the temperature of $Y$ is $400 \, K$. If the mass of the gas in $X$ is $m$,what will be the mass of the gas in $Y$?

Equal molar amounts of $H_2$ and $He$ are placed in two separate containers of equal volume at the same temperature. Their molar masses are $2$ and $4$ respectively. If the pressure of $H_2$ gas is $4 \ atm$,what will be the pressure of $He$ gas in atmospheres?

What is Avogadro number? Write its value.

Which relation is correct for the given $P-V$ diagram?