Practical Work — Chemistry STD 10 — Question

i) Bluish green crystalline solid, on heating, melts to form a bluish green mass and gives off steamy vapours which condense on the cooler part of the test tube.
ii) On further heating, the bluish green mass changes to a black residue.
iii) It gives off a reddish brown gas and gives a gas which rekindles a glowing splinter, i.e. oxygen.