Equal volume of $2$ gases $A$ and $B$ diffuse in $20 \ s$ and $10 \ s$ respectively. If molar mass of $A$ is $80$,then the molar mass of $B$ is:

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?

Define surface tension and provide its dimensions and $SI$ unit.

$A$ mixture of equal masses of two gases with molecular weights $4$ and $40$ has a total pressure of $1.1 \, atm$. The partial pressure of the lighter gas in the mixture is ............ $atm$.

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 $x$)

In a mixture of $CO_2$ and $CH_4$ in a closed vessel at a constant temperature,the total pressure is $8.3 \times 10^4 \, Pa$. If the partial pressure of $CO_2$ is $2.8 \times 10^4 \, Pa$,what will be the partial pressure of $CH_4$?