$3$ moles of mono-atomic gas $(\gamma = 5/3)$ is mixed with $1$ mole of a diatomic gas $(\gamma = 7/5)$. The value of $\gamma$ for the mixture will be

$A$ vessel of volume $0.02 \, m^3$ contains a mixture of hydrogen and helium at $20 \, ^oC$ and $2$ atmospheric pressure. The mass of the mixture is $5 \, g$. Find the ratio of the mass of hydrogen to that of helium in the mixture.

Two vessels of equal volume contain the same gas. Their pressures and temperatures are $P_1, T_1$ and $P_2, T_2$ respectively. When they are connected,the common pressure and temperature are $P$ and $T$. Then $P/T$ is equal to:

$A$ gas mixture consists of $3$ moles of oxygen and $5$ moles of argon at temperature $T$. Assuming the gases to be ideal and the oxygen bond to be rigid,the total internal energy (in units of $RT$) of the mixture is

$A$ gas mixture consists of molecules of $A, B$ and $C$ with masses $m_A > m_B > m_C$. Rank the three types of molecules in decreasing order of $(a)$ average $K.E.$,$(b)$ $rms$ speeds.

The specific heat of the mixture of two gases at constant volume is $\frac{13}{6} R$. The ratio of the number of moles of the first gas to the second is $1:2$. The respective gases may be: