A metal (P) on heating in nitrogen gas gives compound Q . Q on treatment with H 2 O gives a colourless gas which when passed through CuS O 4 solution gives a dark blue-violet coloured solution. P and Q respectively, are

Step-by-step solution

P + N 2 → nitride(Q) → H 2 O NH 3 + CuSO 4 → Blue-violet coloured sol. 3   Mg P   +   N 2 → Mg 3 N 2 Q → H 2 O Mg(OH) 2   +   NH 3 Hence P and Q are Mg and M g 3 N 2 respectively.