What's the volume of 34.8 g of hydrogen gas

To solve this problem, let's look for the number of mole

Number of mole of hydrogen gas = mass / molar mass

= 34.8 / 1.00784 * 2

= 34.8 / 2.01568

= 17.265 mol

To calculate the volume

Number of mole = volume / molar volume

Molar volume at STP is 22.4L/mol

Volume = 17.265 mol * 22.4 L/mol

= 386.736L