Write balanced redox reactions for each of the following reactions:
(a) Potassium dichromate `(K_(2)Cr_(2)O_(7))` reacts with hydroiodic acid `(HI)` to produce potassium iodide, chromium (III) iodide, and solid iodine, `I_(2)(s)`.
(b) A purple solution of aqueous potassium permanganate `(KMnO_(4))` reacts with aqueous sodium sulphite `(Na_(2)SO_(3))` in basic solution to yield the green magnanate ion `(MnO_(4)^(2-))` and sulphate ion `(SO_(4)^(2-))`.
(c ) `Sn^(2+) (aq)` reduce `I_(4)^(Ө)(aq)` to `I^(Ө)(aq)` and is oxidised to `Sn^(4+)`.
(d) `H_(2)O_(2)(aq)` oxidises `Mn^(2+)(aq)` to `MnO_(2)` in basic medium.
(e) `H_(2)O_(2)(aq)` reduces `Cr_(2)O_(7)^(2-) (aq)` to green coloured `Cr^(3+)(aq)` in acidic medium.

Explanation

(i) ` 2MnO_(4)^(-) + 3H_(2)O to 2MnO_(2) + 3O_(2) + 2OH^(-) + 2H_(2)O`
(ii) `10 FeSO_(4) + 2KMnO_(4) + 8H_(2)SO_(4) to 5Fe_(2)(SO_(4))_(3) + 2MnSO_(4) + K_(2)SO_(4) + H_(2)O`
(iii) `2MnO_(4)^(-) + 5C_(2)O_(4)^(2-) + 16H^(+) to 2Mn^(2+) + 10CO_(2) + 8H_(2)O`
(iv) ` K_(2)Cr_(2)O_(7) + 14HCl to 2KCl + 2CrCl_(3) + 7H_(2)O + 3Cl_(2)`