Identify the substance acting as oxidant or reductant if any in the following:
(i) `AlCl_(3)+3KrarrAl+3KCl`
(ii) `SO_(2)+2H_(2)Srarr3S+H_(2)O`
(iii) `BaCl_(2)+Na_(2)SO_(4)rarrBaSO_(4)+2NaCl`
(iv) `3I_(2)+6NaOHrarrNaIO_(3)+5NaI+3H_(2)O`

Explanation

In a conjugate pair, oxidant has higher ox.no.
(i) For `AlCl_(3): Al^(3+)+3erarrAl^(0)`,
therefore Oxidant `AlCl_(3)`
For `K:K^(0)rarrK^(1+)+e`
and reductant `K`. (ii) For `SO_(2):S^(4+)+4erarrS^(0)`, `therefore` Oxidant `SO_(2)`
For `H_(2)S: S^(2-)rarrS^(0)+2e` and reductant `H_(2)S`.
(iii) No change in ox.no. of either of the conjugate pair.
`therefore` None is oxidant or reductant.
(iv) For `I_(2): I_(2)^(0)rarr2I^(5+)+10e`
and `I_(2)^(0)+2erarr2I^(1-)`
`therefore I_(2)` acts as oxidant and reductant both.