Two flasks of equal volume contain $O_2$ and $CH_3OH$ vapor respectively at $120\,^oC$ and $1.15\, atm$ pressure. Which of the following will be the same for both?

The total pressure of a gas and a few drops of water in a container is $830 \, mm$. If the temperature of the container is decreased by $1 \%$,the new pressure is $............ \, mm$. The water vapor pressures at the two temperatures are $30 \, mm$ and $25 \, mm$ respectively.

Liquids flow from a higher level to a lower level. Which of the following liquids climbs up the walls of a glass vessel when filled in it?

At $300 \ K$ and $760 \ torr$ pressure, the density of a mixture of $He$ and $O_2$ gases is $0.543 \ g \ L^{-1}$. The mass percent of oxygen is approximately $(R = 0.0821 \ L \ atm \ K^{-1} \ mol^{-1})$

Assertion: Use of pressure cooker reduces cooking time.
Reason: At higher pressure,cooking occurs faster.

The density of a mixture of $He$ and $O_2$ gases at $27\,^{\circ}C$ and $760\, torr$ pressure is $0.543\, g\, dm^{-3}$. Calculate the percentage by mass of $He$ in the mixture.