The rate of diffusion of a gas $A$ is $\sqrt{5}$ times more than that of gas $B$. If the molar mass of $A$ is $x \ g \ mol^{-1}$, the molar mass of $B \ (\text{in } g \ mol^{-1})$ is (in $x$)

Equal masses of helium and oxygen are mixed in an empty container at $25^{\circ} C$. What is the fraction of the total pressure exerted by helium?

The ratio of rates of diffusion of gases $X$ and $Y$ is $1:5$ and that of $Y$ and $Z$ is $1:6$. The ratio of rates of diffusion of $Z$ and $X$ is

Gas $A$ diffuses $6$ times faster than hydrogen gas. What is the molar mass of $A$?

Which one of the following statements is wrong for gases?

Gaseous state is characterised by which of the following physical properties?
$I$. Gases mix evenly and completely in all proportions without any mechanical aid.
$II$. Gases exert pressure in all directions evenly.
$III$. Gases are highly compressible and have lower density than liquids and solids.
$IV$. The volume and shape of the gas is fixed.