$4 \ g \ CH_4$ and $2 \ g \ He$ are mixed under $NTP$. What is the partial pressure of $He$?

Which one of the following is the kinetic energy of a gaseous mixture containing $3 \ g$ of hydrogen and $80 \ g$ of oxygen at temperature $T(K)$ (in $RT$)?

At the same temperature and pressure,the rate of diffusion of helium with respect to methane is ...... .

Identify the incorrect statement among the following:

The vapor pressure of water at $80\,^oC$ is $355.5\, mm\, of\, Hg$. $A$ $100\, mL$ vessel contains $O_2$ saturated with water vapor at $80\,^oC$,and the total pressure is $760\, mm\, of\, Hg$. If the contents are transferred to a $50\, mL$ vessel at the same temperature,what will be the partial pressure of $O_2$ in $mm\, Hg$?

$CH_4$ diffuses two times faster than a gas $X$. The number of molecules present in $32 \ g$ of gas $X$ is ($N$ is Avogadro number).