State which of the following are reduction reaction and which are oxidation

(i) Pb ⟶ Pb²⁺ + 2e^-

(ii) Fe²⁺ - e^- ⟶ Fe³⁺

(iii) A³⁺ + e^- ⟶ A²⁺

(iv) Cu ⟶ Cu²⁺

(i) Oxidation, since there is a loss of 2 electrons by Lead (Pb).

(ii) Oxidation, since there is a loss of an electron by Iron (Fe).

(iii) Reduction, since there is a gain of an electron by A.

(iv) Oxidation, since there is a loss of 2 electrons by Copper (Cu).