In the relation $n = \frac{PV}{RT}$,what does $n$ represent?

$A$ container holds $6 \ g$ of oxygen at a pressure $P$ and temperature $400 \ K$. $A$ small hole is made in the container so that oxygen can leak out. How much oxygen (in $g$) will leak out by the time the pressure becomes $P/2$ and the temperature becomes $300 \ K$?

$A$ vessel that can withstand a pressure of $100 \,atm$ is filled with hydrogen at $27^{\circ} C$ up to a pressure of $20 \,atm$. If the vessel is heated, then the temperature at which it explodes is (in $\,K$)

We write the relation for Boyle's law in the form $PV = C$ when the temperature remains constant. In this relation,the magnitude of $C$ depends upon

$A$ vessel has $8 \ g$ of oxygen at pressure $P$ and temperature $400 \ K$. $A$ small hole is made in it so that oxygen leaks out. How many grams of oxygen leak out if the final pressure is $P/4$ and the temperature is $200 \ K$?

$A$ gas at absolute temperature $300\,K$ has pressure $P = 4 \times 10^{-10}\,N/m^2$. Given the Boltzmann constant $k = 1.38 \times 10^{-23}\,J/K$,the number of molecules per $cm^3$ is of the order of: