For the diffusion of a gas at pressure $P$,the rate of diffusion is expressed by :

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?

If some moles of $O_2$ diffuse in $18 \ sec$ and the same moles of another gas diffuse in $45 \ sec$,what is the molecular weight of the unknown gas?

The ratio of rates of diffusion of gases $A$ and $B$ is $1 : 0.707$. If the molecular weight of $B$ is $32$,the molecular weight of $A$ is

Which one is not a correct mathematical equation for Dalton's Law of partial pressure? Here $p =$ total pressure of the gaseous mixture.

Consider the following statements: For diatomic gases,the ratio $C_p/C_v$ is equal to:
$1$. $1.40$ (lower temperature)
$2$. $1.66$ (moderate temperature)
$3$. $1.29$ (higher temperature)
Which of the above statements are correct?