Mountaineers carry oxygen cylinders with them because ...

$A$ bulb contains $1 \ g$ of $H_2$ and $1 \ g$ of $He$. If the total pressure is $1.2 \times 10^3 \ Pa$,then the partial pressure of $He$ is ............. $Pa$.

At $T \ K$,equal weights of $H_2, D_2$,and $T_2$ are present in a closed vessel. The pressure exerted by this gaseous mixture is $P \ atm$. The ratio of partial pressures of $T_2, D_2$,and $H_2$ is approximately. ($H, D$ and $T$ are isotopes of hydrogen).

Under the same conditions of pressure and temperature,the same volume of two gases $A$ and $B$ diffuse through a porous partition in $20 \ s$ and $10 \ s$ respectively. The molecular mass of $A$ is $49 \ u$. The molecular mass of $B$ will be ............. $u$.

$A$ sample of $O_2$ gas is collected over water at $23\,^oC$ at a barometric pressure of $751\, mm\, Hg$ (vapour pressure of water at $23\,^oC$ is $21\, mm\, Hg$). The partial pressure of $O_2$ gas in the sample collected is

Pressure-volume $(pV)$ work done by an ideal gaseous system at constant volume is (where $E$ is internal energy of the system):