$A$ mixture of $28 \ g$ of nitrogen,$4 \ g$ of hydrogen,and $8 \ g$ of helium is kept in a vessel at a temperature of $400 \ K$ and a pressure of $8.3 \times 10^5 \ Pa$. What is the density of the mixture?

Three closed vessels $A, B$ and $C$ are at the same temperature $T$ and contain gases which obey the Maxwellian distribution of velocities. Vessel $A$ contains only $O_2$,$B$ only $N_2$ and $C$ a mixture of equal quantities of $O_2$ and $N_2$. If the average speed of the $O_2$ molecules in vessel $A$ is $V_1$,and that of the $N_2$ molecules in vessel $B$ is $V_2$,what is the average speed of the $O_2$ molecules in vessel $C$?

In a cubic container of inner side length $10 \ cm$, nitrogen gas at $100 \ kPa$ pressure is maintained at $300 \ K$. If the pressure inside the container is increased to $300 \ kPa$ by adding oxygen gas, the ratio of the number of $N_2$ molecules to $O_2$ molecules in the container is:

In a thermally isolated system,two boxes filled with an ideal gas are connected by a valve. When the valve is in the closed position,the states of box $1$ and $2$ respectively are $(1 \, atm, V, T)$ and $(0.5 \, atm, 4V, T)$. When the valve is opened,the final pressure of the system is approximately ............... $atm$.

For a mixture of non-reactive gases,derive the equation for total pressure.

$A$ mixture of ideal gases consists of $7 \, kg$ of nitrogen and $11 \, kg$ of $CO_2$. Then (Take $\gamma$ for nitrogen and $CO_2$ as $1.4$ and $1.3$ respectively):