Solution:

Using the ideal gas law in terms of density, $P = \frac{\rho RT}{M}$, we get $\rho = \frac{PM}{RT}$. For hydrogen, $M = 2 \times 10^{-3} \text{ kg/mol}$. Thus, $\rho = \frac{249 \times 10^3 \times 2 \times 10^{-3}}{8.3 \times 300} = 0.2 \text{ kg/m}^3$.