Question

Assertion: Alkyl iodide can be prepared by treating alkyl chloride/bromide with Nal in acetone.
Reason: NaCl/NaBr are soluble in acetone while Nal is not.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (C)

This is Finkelstein reaction which involves the conversion of an alkyl chloride/bromide to an alkyl iodide by the addition of sodium iodide in acetone. Because sodium iodide is soluble in acetone and $NaCl$ and $NaBr$ are not, the equilibrium is shifted by the precipitation of insoluble salt.
$R-X\underset{MX}{\overset{M{X}^{\prime }}{\rightleftharpoons }}R-X^{\prime }$
The equilibrium position of the reaction depends on the nucleophilicity of the anion, whether a good leaving group is present and whether one anion is better stabilised than the other in a given solvent.