Whichd of the following can act as oxidising as well as reducing agent ?

Options

A. `1,2,3`
B. `2,3,4`
C. `1,3,4`
D. All

Answer

C

Explanation

1. `H_(2)O_(2)` undergoes oxidaton to `O_(2)` and also undergoes reduction to give `H_(2)O` (`-1` oxidation state to `0` and `-2`).
2. `S^(2-)` undergoes only oxidation either to `S,SO_(2)` or `SO_(4)^(2-)` in which oxidation number changes from `-2` to `0,+4`, or +6`
`3. `SO_(2)` (oxidation number of `S` is `+4`) can undergo oxidation and reductio. `S` is having highest oxidation state of `+6`. The element in a molecule having its oxidation state in the middle (i.e. minimum and lt maximum) can be used os oxidant and as reductant both.
4. `HNO_(2)` (oxidation number of `N` is `+3`). Highest oxidation state of `N` is `+5`. So it can undergo both oxidant and reductant.