Neco 2017 Chemistry Question 20

Practice objective / multiple choice question 20 from the 2017 Neco Chemistry examination.

Neco 2017 Chemistry Objective / Multiple Choice Hard Difficulty

Question 20 NECO • 2017 • CHEMISTRY • objective

An aqueous solution of an unknown metal salt is subjected to the following qualitative tests:\n1. Addition of dilute \(\text{HCl}\): no visible change.\n2. Addition of dilute \(\text{NH}_4\text{OH}\): a pale‑blue precipitate forms which dissolves on adding excess \(\text{NH}_4\text{OH}\), giving a deep‑blue solution.\n3. Introduction of \(\text{H}_2\text{S}\) gas in acidic medium (pH≈1): no precipitate.\n4. Addition of \(\text{NaOH}\): a blue precipitate forms which also dissolves in excess \(\text{NH}_4\text{OH}\).\n5. Addition of \((\text{NH}_4)_2\text{S}\) in alkaline medium: a black precipitate appears instantly. Identify the metal ion present in the solution.

A. Co^{2+}

Correct Answer B. Cu^{2+}

C. Ni^{2+}

D. Zn^{2+}

Correct Answer

Correct Option:

Cu^{2+}

This is Neco 2017 Chemistry Question 20. It is one of the objective questions from the 2017 Neco Chemistry examination.

Difficulty level: Hard .

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