At what $^o C$ temperature,the sample of neon gas would be heated to double its pressure,if the initial volume of gas is reduced to $15\%$ at ${75\,^o}C$?

At $273\,K$,$Pd$ vs $P$ is plotted for various gases $1, 2, 3, 4$. Assuming ideal behaviour for four gases $N_2, He, CO_2$ & $H_2$. The correct combination is [$P$ denotes pressure in atmosphere & $d$ denotes density in $g/L$]

Two closed vessels of equal volume containing air at pressure $P_1$ and temperature $T_1$ are connected to each other through a narrow tube. If the temperature in one of the vessels is now maintained at $T_1$ and that in the other at $T_2$,what will be the final pressure in the vessels?

At what temperature in $^\circ C$ will the volume of a gas become double its volume at $0\,^\circ C$?

In the equation $PV = nRT$,which of the following is $NOT$ equal to the value of $R$?

When $2 \ g$ of a gaseous substance $A$ is introduced into an initially evacuated flask at $25^{\circ} C$,the pressure is found to be $1 \ atm$. $3 \ g$ of another gaseous substance $B$ is added to it at the same temperature and pressure. The final pressure is found to be $1.5 \ atm$. Assuming ideal gas behaviour,the ratio of molar masses of $A$ and $B$ is: