Pressure of a gas of constant volume at $20^{\circ} C$ is $90 \ cm$ of $Hg$. At what temperature the pressure would change to $75 \ cm$ of $Hg$ (in $^{\circ} C$)?

$A$ gas is contained in a $5 \, L$ vessel at a pressure of $0.8 \, m$. It is connected to another evacuated vessel of $3 \, L$ capacity. What will be the resultant pressure in $m$ (at constant temperature)?

Equal masses of $N_2$ and $O_2$ gases are filled in containers $A$ and $B$ respectively. The volume of container $B$ is twice the volume of container $A$. What is the ratio of the pressure in container $A$ to that in container $B$?

$A$ balloon is filled with $500 \,m^3$ of helium gas at $27^{\circ} C$ and $1 \,atm$ pressure. What will be the volume of the helium gas at $-3^{\circ} C$ and $0.5 \,atm$ pressure (in $\,m^3$)?

The number of air molecules in a $(5 \,m \times 5 \,m \times 4 \,m)$ room at standard temperature and pressure is of the order of

The temperature of a gas at pressure $P$ and volume $V$ is $27^{\circ}C$. Keeping its volume constant,if its temperature is raised to $927^{\circ}C$,then its pressure will be (in $P$)