Question

The reducing agent in the given equations :
\(4\ Ag_{(s)}+8\ CN_{(aq)}^-+2H_2O_{(aq)}+O_{2_{(g)}}\rightarrow4[Ag(CN)_2]_{(aq)}^-+4\ OH_{(aq)}^-\)
\(2[Ag(CN)_2]_{(aq)}^-+Zn_{(s)}\rightarrow[Zn(CN)_4]_{(aq)}^{2-}+2Ag_{(s)}\)

• A. CN^-
• B. O₂
• C. H₂
• D. Zn

Answer 1

The Correct Option is A

The given chemical reactions are:

Reaction 1:

\[ 4 \, \text{Ag}^+ (s) + 8 \, \text{CN}^- (aq) + 2 \, \text{H}_2\text{O} (aq) + \text{O}_2 (g) \rightarrow 4 \, [\text{Ag(CN)}_2]^- (aq) + 4 \, \text{OH}^- (aq) \] In this reaction, silver ion (\(\text{Ag}^+\)) is reduced to \([\text{Ag(CN)}_2]^-\), and oxygen (\(\text{O}_2\)) is involved as the oxidizing agent. Since silver ions are reduced, **cyanide ions (CN⁻)** are oxidized, making them the reducing agent.

Reaction 2:

\[ 2 \, [\text{Ag(CN)}_2]^- (aq) + \text{Zn} (s) \rightarrow [\text{Zn(CN)}_4]^{2-} (aq) + 2 \, \text{Ag} (s) \] Here, zinc metal (\(\text{Zn}\)) is oxidized to \(\text{Zn}^{2+}\), while the silver ions (\(\text{Ag}^+\)) are reduced to metallic silver. Since zinc is losing electrons, it is the reducing agent in this reaction.

Conclusion:

In both reactions, the **reducing agent is CN⁻ (cyanide ion)**, as it is responsible for reducing the metal ions (\(\text{Ag}^+\) and \(\text{Zn}^{2+}\)).

Correct Answer: Option (A): CN⁻

Answer 2

In the given equations, a reducing agent is a substance that donates electrons to another substance, thereby reducing it. In the first equation, the silver ion (Ag⁺) is reduced to form the complex ion \([\text{Ag(CN)}_2]^- \), and in the second equation, zinc (Zn) is oxidized to form \([\text{Zn(CN)}_4]^{2-}\) while reducing silver ions (Ag⁺) to silver metal (Ag).

Thus, zinc (Zn) acts as the reducing agent because it donates electrons, causing the reduction of silver ions in the second equation. Hence, the correct answer is (A) Zn.