SN1 hydrolysis of tertiary iodoalkane yields I⁻, forming yellow AgI precipitate

Steps:

• SN1 reaction with warm water requires tertiary halogenoalkane, as it proceeds via carbocation intermediate.
• Hydrolysis produces alcohol and halide ion (X⁻).
• Adding AgNO₃(aq) to the mixture tests for X⁻ via precipitation of AgX.
• Yellow AgI precipitate identifies X as iodide (AgCl white, AgBr pale yellow/cream).

Why D is correct:

• 2-iodo-2-methylpropane is tertiary iodide; SN1 favored by 3° structure, and AgI forms yellow ppt per solubility rules (AgI least soluble, yellow color).

Why the others are wrong:

• A: Primary chloride favors SN2, not SN1; AgCl white ppt.
• B: Primary iodide favors SN2, not SN1; doesn't meet reaction condition.
• C: Tertiary chloride undergoes SN1, but AgCl white ppt.

Final answer: D