$20 \ mL$ of gas $A$ and $10 \ mL$ of gas $B$ diffuse through a porous membrane separately in $1 \ minute$. If the vapour density of $B$ is $x$,what is the vapour density of $A$?

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.

Identify the correct statements from the following.
$I$. Glass is an extremely viscous liquid.
$II$. Increase in temperature decreases the surface tension of liquids.
$III$. Compressibility factor for an ideal gas is zero.

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

Which of the following is a superfluid?

Ice and water are placed in a closed container at a pressure of $1 \ atm$ and temperature $273.15 \ K$. If the pressure of the system is increased $2$ times,keeping the temperature constant,then identify the correct observation from the following: