Hydrogen density at standard temperature and pressure (0 °C, 101.325 kPa) is:
[tex]\rho_{H_2} = \frac{g}{L}[/tex]
The mass is the product between density and volume:
[tex]m_{H_2}=\rho_{H_2} \cdot V_{H_2} = 0.08988 \cdot 2.4 \cdot 10^4 = 21571.2[/tex] grams
The weight in kg will be 21.5712 kg