question_answer 87)

  A metal M does not liberate hydrogen from adds but reacts with oxygen to give a black colour product. Identify M and black coloured product and also explain the reaction of M with oxygen.

Answer:

                  Metal M is Cu as Cu is less reactive than hydrogen. So, it does not react with acid to liberate hydrogen.                 Copper metal does not burn in air even on strong heating. Copper reacts with the oxygen of air on prolonged heating to form a black substance copper (II) oxide.