Nucleophilic substitution test for alkyl halides with AgNO₃

Steps:

• Alkyl halides like CH₃I undergo substitution with AgNO₃(aq), where Ag⁺ promotes halide departure.
• The reaction forms a silver halide precipitate: CH₃I + AgNO₃ → CH₃NO₃ + AgI.
• This is nucleophilic substitution, as Ag⁺ acts as a nucleophile attacking the carbon, displacing I⁻.
• AgI precipitate is yellow, observed at 50°C.

Why D is correct:

• Nucleophilic substitution occurs because the C–I bond breaks heterolytically with Ag⁺ as the nucleophile, and AgI is yellow per standard halide tests.

Why the others are wrong:

• A: Electrophilic substitution does not apply; haloalkanes react via nucleophilic pathways.
• B: Electrophilic substitution is incorrect; mechanism is nucleophilic.
• C: Color is wrong; AgI is yellow, not cream (cream is AgCl).

Final answer: D