Question

At 0.0°C and 1.00 atm, 1.00 mol of a gas occupies a volume of 0.0224 m³.

 What is the number density?

Answer 1

$$P=nkT$$

$$n=\frac{P}{kT}=\frac{101.3*10^3}{1.38*10^{-23}*273}=2.7*10^{25}\:\rm m^{-3}$$