Question

Identify the oxidant and reductant in the following reactions:
a. `10^(o+)(aq)+4Zn(s)+NO_(3)^(ө)(aq)rarr4Zn^(2+)(aq)+NH_(4)^(o+)(aq)+3H_(2)O(l)`
b. `I_(2)(g)+H_(2)S(g)rarr2Hl(g)+S(s)`

Answer 1

Correct Answer - A::B::C::D
In a reaction (a), there is no change in the oxidation number of `H` and `O`. Oxidation number of `Zn` changes from `0` to `+2` and therefore, it is oxidised and hence acts as a reductant. The oxidation number of `N` in nitrite ion is `+5` and in ammonium ion it is `-3`, and therefore, it is reduced and acts as an oxidant.
In reaction (b) the oxidation number of `I` changes from `0` to `-1`. Therefore, it is redced and acts as an oxidant. The oxidation number of `S` in `H_(2)S` changes from `-2` to `0`. Therefore, it is oxidised and hence acts as a reductant.