0.5 g = 0.5 mol of (atomic, not molecular) hydrogen, so 0.5 mol of electrons was absorbed by the hydrogen.
In CuSO₄, copper is in a +2 oxidation state, so it takes 2 mol of electrons per 1 mol Cu to liberate it. Only 0.5 mol of electrons is provided, which is 0.25 of 2 mol, so it would be able to liberate only 0.5/2 = 0.25 mol Cu.
Now look up the molar mass of copper and multiply.
Answers & Comments
0.5 g = 0.5 mol of (atomic, not molecular) hydrogen, so 0.5 mol of electrons was absorbed by the hydrogen.
In CuSO₄, copper is in a +2 oxidation state, so it takes 2 mol of electrons per 1 mol Cu to liberate it. Only 0.5 mol of electrons is provided, which is 0.25 of 2 mol, so it would be able to liberate only 0.5/2 = 0.25 mol Cu.
Now look up the molar mass of copper and multiply.