How many times the volume of a diatomic gas should be increased reversibly and adiabatically in order to reduce its $RMS$ velocity to half of its initial value?

The density of $CO_2$ at $100\,^oC$ temperature and $400\,mm\,Hg$ pressure is .......... $g/L$.

$A$ glass vessel weighs $50.0 \, g$ when empty. When filled with a liquid of density $0.98 \, g \cdot mL^{-1}$,it weighs $148.0 \, g$. When filled with an ideal gas at $760 \, mm$ of $Hg$ pressure and $300 \, K$ temperature,it weighs $50.5 \, g$. Calculate the molar mass of the gas in $u$.

An ideal gas expands isothermally and reversibly from $10 \ m^3$ to $20 \ m^3$ at $300 \ K$,performing $5.187 \ kJ$ of work on the surroundings. Calculate the number of moles of gas used.

At $25 \, ^oC$ and $730 \, mm$ pressure,$380 \, mL$ of dry oxygen gas is collected. If the temperature is kept constant,what will be the volume of oxygen gas at $760 \, mm$ pressure (in $, mL$)?

Identify the correct observation with respect to the given graphs.