Answer: 6.0 moles
Step-by-step explanation:
1) The information in the quesiton is incomplete.
2) The question is bases on a voltaic cell in which the reactants are
Al (NO₃) ₃ (aq) + Ni (NO₃) ₂ (aq).
3) And you are also given the net ionic reaction:
2Al(s) + 3Ni²⁺ (aq) → 2Al₃ (aq) + 3Ni(s)
4) It is from the net ionic reaction that you get the ration between Al and Ni:
2 moles of Al react with 3 moles of Ni, so you can state the proportion:
2 moles Al / 3 moles Ni = x / 9.0 moles Ni
5) So, you just must solve for x:
x = 9.0 moles Ni × 2 moles Al / 3 mols Ni = 6.0 moles Al