WAEC Chemistry 2025 Objective — Question 47

Question 47 of 50 from the West African Examinations Council (WAEC) Chemistry 2025 Objective paper, with the correct answer and a full explanation.

A few drops of sodium hydroxide are added to an aqueous solution, and a green precipitate is formed. The ion that may be present in the solution is

A. Cu2+
B. Fe2+Correct
C. NH4+
D. Fe3+

Explanation

When iron (II) ion (Fe2+) reacts with sodium hydroxide, it forms a green precipitate of iron (II) hydroxide, Fe(OH)2. NB: Cu2+ forms a blue precipitate with sodium hydroxide, NH4+ does not form a precipitate, and Fe3+ forms a brown precipitate of iron (III) hydroxide.

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