Which of the following is zero for an $isochoric$ process?

$X \ mL$ of $H_2$ gas effuses through a hole in a container in $5 \ s$. The time taken for the effusion of the same volume of the gas specified below under identical conditions is:

If a saturated vapor is slowly compressed (at constant temperature) to half of its initial volume,what happens to the vapor pressure?

$A$ 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 $21\,mm\,Hg$)

Equal amounts of two gases of molecular weights $4$ and $40$ are mixed. The pressure of the mixture is $1.1 \ atm$. What will be the partial pressure of the lighter gas in the mixture (in $atm$)?

For which of the following gas mixtures does Dalton's law of partial pressure $NOT$ apply?