Task 1.5d.1 constructing half equations

Put in numbers hydrogen ions water molecules and electrons to balance the following half equations:
(a)  Sn²⁺(aq)                  ----->              Sn⁴⁺(aq)
(b)  Cl^-(aq)                     ----->              Cl₂(aq)
(c)  SO₃^2-(aq)                ----->              SO₄^2-(aq)
(d)  MnO₄^-(aq)               ----->              Mn²⁺(aq)
(e)  Cr₂O₇^2-(aq)             ----->              Cr³⁺(aq)