Isochores are drawn at

$A$ vessel of $2.461 \ L$ contains a mixture of $0.3 \ mol$ of $N_2$,$0.5 \ mol$ of $He$,and $6.2 \ mol$ of $O_2$ at $27 \ ^oC$. What is the partial pressure of $N_2$ in the mixture in $atm$?

In a container,the mole ratio of two gases $A$ and $B$ is $2 : 5$. The total pressure of the container is $3.5 \times 10^5 \ Pa$. If all molecules of $A$ are removed from the container,what will be the pressure exerted by the molecules of $B$?

If the rate of diffusion of $A$ is $5$ times the rate of diffusion of $B$,what will be the ratio of the densities of $A$ and $B$?

Which of the following statements is correct?

At a given temperature,the rate of diffusion of methane is twice that of gas $X$. The molecular weight of $X$ is ...... .