How many electrons are in 1 mol of hydrogen gas?

No. of H₂ molecules in 1 mol of hydrogen gas = 6.022 × 10²³

Each H₂ (H-H) molecule contains 2 electrons.
Hence, no. of electrons in 1 mol of hydrogen gas = (6.022 × 10²³) × 2 = 1.204 × 10²⁴ (to 4 sig. fig.)

1 mol H₂ * 6.022 * 10²³ molec/mol = 6.022 * 10²³ molec H₂
6.022 * 10²³ molec H₂ * 2 atoms/molec = 1.2044 * 10²⁴ atoms H₂ = 1.2044 * 10²⁴ electrons

6.02x10^23.