Matching Organic and Inorganic Species with Reactions and Properties

Step-by-step Evaluation:

1. (A) Benzaldehyde ($\text{C}_6\text{H}_5\text{CHO}$):

• Contains a carbonyl group (aldehyde), so it gives an orange-red precipitate of 2,4-dinitrophenylhydrazone with Brady's reagent ($p$).
• It reacts with $\text{HCN}/\text{CN}^-$ to form a cyanohydrin, meaning it is directly involved in cyanohydrin formation ($s$).
• Matching: $(\text{A}) \rightarrow (\text{p}, \text{s})$.

1. (B) Propyne ($\text{CH}_3\text{C}\equiv\text{CH}$):

• Contains a terminal acetylenic hydrogen (acidic proton), which reacts with ammoniacal $\text{AgNO}_3$ (Tollens' reagent) to yield a white/pale-yellow precipitate of silver propynide ($q$).
• Matching: $(\text{B}) \rightarrow (\text{q})$.

1. (C) Cyanide ion ($\text{CN}^-$):

• Reacts with silver nitrate to precipitate insoluble silver cyanide $\text{AgCN}$ ($q$).
• Possesses a lone pair of electrons on carbon and acts as a powerful nucleophile ($r$).
• Attacks carbonyl groups in aldehydes/ketones to form cyanohydrins, so it is involved in cyanohydrin formation ($s$).
• Matching: $(\text{C}) \rightarrow (\text{q}, \text{r}, \text{s})$.

1. (D) Iodide ion ($\text{I}^-$):

• Reacts with $\text{Ag}^+$ to form a bright yellow precipitate of silver iodide $\text{AgI}$ ($q$).
• Possesses valence electron pairs and behaves as an effective nucleophile in substitution reactions ($r$).
• Matching: $(\text{D}) \rightarrow (\text{q}, \text{r})$.

Matching:
$(\text{A}) \rightarrow (\text{p}, \text{s}),\; (\text{B}) \rightarrow (\text{q}),\; (\text{C}) \rightarrow (\text{q}, \text{r}, \text{s}),\; (\text{D}) \rightarrow (\text{q}, \text{r})$

Correct Answer: D