If the hydrogen volume reads 8.35 mL, what number of moles does the represent at STP (1 atm and 0oC)?

How many moles of electrons were added to the solution to create 8.35 mL of hydrogen gas?

8.35 mL x (1 mol/22,400 mL) = ? mols H2.

Is this H2 gas from H^+ in solution?
2H^+(aq) + 2e ==> H2(g)

mols e = 2*mols H2 gas (again, look at the coefficients.)