Justify that the following reactions are redox reactions :
`4NH_(3)(g)+5O_(2)(g)to4NO(g)+6H_(2)O(g)`

Explanation

`overset(-3)(4N) overset(+1)(H_(3)) (g) + 5 O_(2)^(0)(g) rarr overset(+2)(4N) overset(-2)(O)(g) + overset(+1)(6H_(2)) overset(-2)(O)(g)`
In this reaction, the oxidation state of N is increasing from -3 (in `NH_(3)`) to +2 (in NO), hence, `NH_(3)` is undergoing oxidation. While the oxidation number of oxygen is decreasing from 0 (in `O_(2)`) to -2 (in `H_(2)O`) , hence, `O_(2)` is undergoing reduction. Therefore, it is a redox reaction.