The volume of $1$ mole of any pure gas at standard temperature and pressure $(STP)$ is always equal to (in $m^3$)

At $400 \ K$ temperature in a closed vessel,the $\%$ by volume of $He, Ne$,and $Ar$ are $40\%, 40\%$,and $20\%$ respectively. If the total pressure is $25 \ bar$,find the partial pressure of each gas.

What is the density of water vapour at the boiling point of water?

The rate of diffusion of two gases $x$ and $y$ is $10 \, mL/s$ and $40 \, mL/s$ respectively,then the ratio of their molar masses $(Mw_x : Mw_y)$ is

What is the difference between a barometer and a manometer?

$2.0 \ g$ of $H_2$ diffuses through a porous container in $10 \ minutes$. How many grams of $O_2$ would diffuse from the same container in the same time under similar conditions (in $.0$)?