A black compound of manganese reacts with a halogen acid to give greenish yellow gas . When excess of this gas reacts with `NH_(3)` an unstable trihalide is formed. In this process, the oxidation state of nitrogen changes from

Options

A. `-3 ` to +3
B. `-3` to 0
C. `-3 ` to +5
D. 0 to -3

Answer

A

Explanation

Black coloured compound `MnO_(2)` reacts with HCl to produce greenish yellow coloured gas of `Cl_(2)`
`underset("black")MnO_(2)+4HCl to MnCl_(2)+2H_(2)O+underset("greenish yellow gas")(Cl_(2))`
`Cl_(2)` on further treatment with `NH_(3)` produces `NCl_(3) overset(-3)NH_(3)+3Cl_(2) to overset(+3)NCl_(3)+3HCl`
`NH_(3)(-3)` changes to `NCl_(3)(+3)` in the above reaction.