2. CuCl₂·2H₂O is limiting reactant.
Chemical reaction: 3CuCl₂·2H₂O + 2Al → 3Cu + 2AlCl₃ + 6H₂O. m(Al) = 0,5 g.

3 MgCl2 + 2 Al = 3 Mg + 2 AlCl3
Since we know that we have 12 moles of MgCl2 and enough Al, we don't need to figure out the exact amount of Al.
3 MgCl2 / 2 AlCl3 = 12 mol MgCl2 / x mol AlCl2
cross-multiply
3 MgCl2(x mol AlCl2) = 12 mol MgCl2(2 AlCl3)
3x = 24
x=8
8 moles AlCl3
Alternatively, we know that we have 12 moles of MgCl2, and a coefficient of 3. This indicates a multiplier of 4 for the entire equation, meaning 2 AlCl3 multiplied by (4) = 8 moles
The answer to this question would be: the anion uptake will be decreased
If proton pump function is decreased, that means the amount of proton that goes outside the cell will be decreased. It will cause the anion uptake decreased too because some anion needs to go inside cells by co transporting with the proton.