Equal volumes of monoatomic and diatomic gases at same initial temperature and pressure are mixed. The ratio of specific heats of the mixture $({C_p}/{C_v})$ will be

Two gases $X$ (molecular weight $M_{X}$) and $Y$ (molecular weight $M_{Y}$; $M_{Y} > M_{X}$) are at the same temperature $T$ in two different containers. Their root mean square velocities are $C_{X}$ and $C_{Y}$ respectively. If the average kinetic energies per molecule of two gases $X$ and $Y$ are $E_{X}$ and $E_{Y}$ respectively, then which of the following relation$(s)$ is(are) true?

At constant temperature,$200 \ cm^3$ of $N_2$ at $720 \ mm$ pressure and $400 \ cm^3$ of $O_2$ at $750 \ mm$ pressure are taken in a $1 \ L$ flask. What will be the total pressure of the mixture in $mm$?

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

Two statements are given below.
Statement-$I$: Viscosity of liquid decreases with increase in temperature.
Statement-$II$: The units of viscosity coefficient are Pascal sec.
The correct answer is

An empty $LPG$ cylinder weighs $14.8 \ kg$. When full,it weighs $29.0 \ kg$ and shows a pressure of $3.47 \ atm$. In the course of use at ambient temperature,the mass of the cylinder is reduced to $23.0 \ kg$. The final pressure inside of the cylinder is $....... \ atm$. (Nearest integer)
(Assume $LPG$ to be an ideal gas)