Question

Impure silver ore + CN⁻ + H₂O → [X]⁻ + OH⁻
[X]⁻ + Zn → [Y]²⁺ + Ag (pure)
The co-ordination numbers of the metals in [X], [Y] are respectively:

• A. 3, 4
• B. 1, 4
• C. 2, 4
• D. 2, 2

Hint:

In coordination chemistry, the coordination number of a metal ion refers to the number of ligands attached to it. Common coordination numbers for transition metals are 2, 4, and 6.

Answer 1

The Correct Option is D

The given chemical reactions are as follows:

Impure silver ore + CN⁻ + H₂O → [X]⁻ + OH⁻

[X]⁻ + Zn → [Y]²⁺ + Ag (pure)

In the first reaction, silver ions from the impure ore react with cyanide ions (CN⁻) to form a complex [X]⁻, which is a silver cyanide complex. The common silver-cyanide complex is [Ag(CN)₂]⁻. The coordination number for silver in this complex is 2 because it is coordinated to two cyanide ions.

In the second reaction, [X]⁻ reacts with zinc to form [Y]²⁺ and pure silver. When zinc displaces silver, a zinc-cyanide complex is formed. The common zinc-cyanide complex is [Zn(CN)₄]²⁻, where the coordination number for zinc is 4 because it is coordinated to four cyanide ions.

Therefore, the coordination numbers of the metals in [X] and [Y] are both 2. The correct option is:

2, 2

Answer 2

In this reaction, impure silver ore reacts with cyanide (CN⁻) and water (H₂O) to form a complex ion [X]⁻. The complex [X]⁻ reacts with zinc (Zn) to form the complex [Y]²⁺ and pure silver (Ag). 
Step 1: The coordination number of the metal in complex [X]⁻, which is silver, is 2. This is because silver typically forms two bonds in its complex ions in the presence of cyanide (CN⁻). 
Step 2: The coordination number of the metal in complex [Y]²⁺, which is zinc, is also 2. Zinc commonly forms two bonds in its coordination compounds, which is confirmed by its interaction with [X]⁻ in the given reaction. 
Step 3: Thus, the coordination numbers of the metals in [X] and [Y] are both 2, making option (4) the correct answer.