What is the number of molecules in $1 \, litre$ of an ideal gas at $S.T.P.$?

At $10^{\circ} C$,the value of the density of a fixed mass of an ideal gas divided by its pressure is $x$. At $110^{\circ} C$,this ratio is:

Find the value of the universal gas constant $R$ in $J \ mol^{-1} K^{-1}$.

In a process,the pressure of an ideal gas varies with volume as $P = \frac{a}{1 + (V/b)^2}$,where $a$ and $b$ are constants. What is the temperature of the gas when the volume of $1$ mole of the gas is $V = b$?

$A$ closed vessel contains $8\,g$ of oxygen and $7\,g$ of nitrogen. The total pressure is $10\,atm$ at a given temperature. If oxygen is now absorbed by introducing a suitable absorbent,the pressure of the remaining gas in $atm$ will be:

The figure shows the isotherms of a fixed mass of an ideal gas at three temperatures $T_A, T_B$ and $T_C$. Then: