State what you would observe when the following substances are heated in a glass test tube:

(i) Red lead

(ii) Copper (II) carbonate

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1 Answers

(i) 2Pb3O4 → 6PbO + O2 ↑

The dark red lead as red powder changes to yellow color. The yellow color residue on further heating sticks to the tube and give a reddish color to glass. A colorless and odorless gas is evolved.

(ii) CuCO3 → CuO + CO2 ↑

The blue-green powder turns black and a colorless gas is evolved which extinguishes a burning flame.

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