What is the temperature at which the kinetic energy of $0.3 \text{ moles}$ of helium is equal to the kinetic energy of $0.4 \text{ moles}$ of argon at $400 \text{ K}$ (in $\text{ K}$)?

Based on the given figure,the number of correct statement/s is/are $........$.
$A.$ Surface tension is the outcome of equal attractive and repulsion forces acting on the liquid molecule in bulk.
$B.$ Surface tension is due to uneven forces acting on the molecules present on the surface.
$C.$ The molecule in the bulk can never come to the liquid surface.
$D.$ The molecules on the surface are responsible for vapour pressure if the system is a closed system.

$A$ and $B$ are ideal gases. The molecular weights of $A$ and $B$ are in the ratio of $1: 4$. The pressure of a gas mixture containing equal weights of $A$ and $B$ is $P \text{ atm}$. What is the partial pressure (in $\text{atm}$) of $B$ in the mixture?

At $27^{\circ} C$, $500 \ mL$ of helium diffuses in $30 \ minutes$. What is the time (in hours) taken for $1000 \ mL$ of $SO_2$ to diffuse under the same experimental conditions?

Explain the fire polishing of glass.