Question

2[Au(CN)₂]^– + Zn \(\to\) [Zn(CN)₄]^2– + 2Au\(\downarrow\) is which of these 
(A) Redox reaction 
(B) Displacement reaction
(C) Combination reaction
(D) Decomposition reaction 

• A. A & B
• B. B only
• C. A & D
• D. B & D

Answer 1

The Correct Option is A

To determine the type of reaction represented by the equation:

\(2[\text{Au(CN)}_2]^– + \text{Zn} \to [\text{Zn(CN)}_4]^{2–} + 2\text{Au}\downarrow\),

let us analyze the nature of the reaction step-by-step.

1. Redox Reaction:
   • In the given reaction, the oxidation states of elements change. Gold (Au) is initially present in the complex \([\text{Au(CN)}_2]^−\) where it has an oxidation state of +1. It is reduced to elemental gold (\( \text{Au} \)) with an oxidation state of 0. This signifies the gain of electrons, indicating reduction.
   • Zinc (Zn) starts with an oxidation state of 0 and is oxidized to form the complex \([\text{Zn(CN)}_4]^{2–}\), in which it has an oxidation state of +2. This signifies the loss of electrons, indicating oxidation.
   • Since both reduction and oxidation occur simultaneously, this reaction can be classified as a redox reaction.
2. Displacement Reaction:
   • In this reaction, zinc metal displaces gold from its complex, leading to the formation of a zinc complex and the release of elemental gold.
   • This type of reaction, where one element displaces another from a compound, is known as a displacement reaction.

Hence, the reaction is classified as both a redox reaction and a displacement reaction. Therefore, the correct answer is A & B.