Chemistry · May / June 2023 · Paper 12 · Question 40

Aqueous sodium hydroxide is used to identify the ions present in aqueous solutions of compounds Q and R. The results are shown. [Diagrams: Q - coloured solution, before addition of aqueous sodium hydroxide; after addition of a few drops of aqueous sodium hydroxide gives green precipitate. R - colourless solution, before addition of aqueous sodium hydroxide; after addition of aqueous sodium hydroxide with heat gives gas given off.] Which row is correct?

1. ACr3+ ; NH4+
2. BCu2+ ; CO3 2–
3. CFe2+ ; CO3 2–
4. DFe3+ ; NH4+

As printed in the paper