$A$ sample of air contains $N_2$ and $O_2$ saturated with water vapor,with a total pressure of $640 \ torr$. If the water vapor pressure is $40 \ torr$ and the molar ratio of $N_2$ to $O_2$ is $3 : 1$,what is the partial pressure of $N_2$ in the sample in $torr$?

At $400 \ K$ temperature in a closed vessel,the $\%$ by volume of $He, Ne$,and $Ar$ are $40\%, 40\%$,and $20\%$ respectively. If the total pressure is $25 \ bar$,find the partial pressure of each gas.

$A$ mixture of one mole each of $H_2$,$He$ and $O_2$ are enclosed in a cylinder of volume $V$ at temperature $T$. If the partial pressure of $H_2$ is $2 \ atm$,the total pressure of the gases in the cylinder is $....... \ atm$

At $27^{\circ} C$, a closed vessel contains a mixture of equal weights of helium (mol. wt. = $4$), methane (mol. wt. = $16$) and sulphur dioxide (mol. wt. = $64$). The pressure exerted by the mixture is $210 \ mm$. If the partial pressures of helium, methane and sulphur dioxide are $p_1, p_2$ and $p_3$ respectively, which one of the following is correct?

At $298 \, K$,equal masses of $SO_2, CH_4$,and $O_2$ are placed in an empty container. The total pressure of the mixture is $2.1 \, atm$. The partial pressure of $CH_4$ in the mixture is ........... $atm$.

$A$ closed vessel contains an equal number of nitrogen and oxygen molecules at a pressure of $P \ mm$. If nitrogen is removed from the system,then the pressure will be