$A$ sample of $O_2$ gas is collected over water at $23\,^oC$ and a barometric pressure of $751\,mm\,Hg$. What is the partial pressure of the $O_2$ gas in this sample? (Vapor pressure of water at $23\,^oC$ is $21\,mm\,Hg$)

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?

The $\%$ composition by volume of $Cl_2, H_2$,and $N_2$ are in $1:2:7$ by proportion. If the total pressure is $40 \ bar$,find the partial pressures of each gas?
[ Partial pressure $= \frac{\text{Volume } \% \times \text{Total pressure}}{100} ]$

In a flask containing $2 \ g$ of $H_2$ and $32 \ g$ of $SO_2$,the partial pressure of hydrogen is.....

$80 \ mL$ of $O_2$ takes $2 \ minute$ to pass through the hole. What volume of $SO_2$ will pass through the hole in $3 \ minute$?

If $N_2, O_2, H_2$,and $He$ gases are filled separately in four car tubes at the same pressure,which gas will diffuse first?