Chemistry · May / June 2026 · Paper 11 · Question 10

A 3.00 g sample of copper ore containing copper(II) carbonate, CuCO3, and inert rock is heated until there is no change in mass. When cool, the residue weighs 2.20 g. The equation shows the decomposition of the carbonate. CuCO3 → CuO + CO2 What is the percentage purity of the ore?

1. A48.5%
2. B71.5%
3. C75.2%
4. D77.4%

As printed in the paper