What happens when oil is added to water? Why?

At $STP$,$0.50 \ mol$ $H_2$ gas and $1.0 \ mol$ $He$ gas:

Two flasks $A$ and $B$ have equal volumes. $A$ is maintained at $300 \ K$ and $B$ at $600 \ K$. Equal masses of $H_2$ and $CO_2$ are taken in flasks $A$ and $B$ respectively. Find the ratio of total $K.E.$ of gases in flask $A$ to that of $B$.

When $0.0168 \, mol$ of $O_2$ obtained from the decomposition of $KClO_3$ is collected over water at $25 \, ^\circ C$,the volume is $428 \, mL$ and the pressure is $754 \, mm$. What is the water vapor pressure at $25 \, ^\circ C$ in $mm$?

Assertion : Ice melts faster at high altitude.
Reason : At high altitude,atmospheric pressure is high.

Two gases $X$ and $Y$ are taken in equal molar proportions. The ratio of their rates of diffusion is $1 : 2$. What will be the mole fraction of $X$ in a mixture containing $2 \ g$ of $X$ and $3 \ g$ of $Y$?