question_answer 57)

    A black compound of manganese reacts with a halogen acid to give greenish yellow gas. When excess of this gas reacts with  an unstable trihalide is formed. In this process the oxidation state of nitrogen changes from.......... (a) -3 to + 3                         (b) -3 to 0 (c) - 3 to + 5                        (d) 0 to ? 3

Answer:

                    (a) Black coloured compound  reacts with HCI to produce greenish yellow coloured gas of Cl2  on further treatment with  produces NCl3.           changes to  in the above reaction. Hence, (a) is the correct choice.