What volume does 0.056 moles of H2 gas occupy @ stp?

At standard temperature and pressure conditions, 1 mol of any gas occupies a volume of 22.4 L. This is known as molar volume.

1 mol of H₂ gas occupies a volume of 22.4 L

Molar volume - 22.4 L/mol

Therefore an amount of 0.056 mol of H₂ takes up - 22.4 L/mol x 0.056 mol

Therefore volume used by 0.056 mol of H₂ - 1.25 L