Question

a compound A is green in colour on heating it gives a gas B which turns limewater milky. the residue left C is black in colour identify A B and C write the chemical reaction involved.

Answer 1

Copper carbonate.

CuCO3 gives on heating CuO + Co2

copper carbonate on heating gives copperoxide and carbondioxide.

Copper carbonate which is light green in colour solid on heating gives a black residue. A colourless gas is evolved which turns the lime water milky.