Question

The decreasing order of reactivity of alkyl halides is ______.

Options

• RI > RCl > RBr

• RBr > RCl > RI

• RI > RBr > RCl

• Cl > RBr > Rl

Answer 1

The decreasing order of reactivity of alkyl halides is RI > RBr > RCl.

Explanation:

1. Alkyl iodides (RI) are the most reactive because the carbon-iodine bond is the weakest among alkyl halides, making it easier to break during substitution reactions.
2. Alkyl bromides (RBr) come next, having a stronger C–Br bond than C–I but weaker than C–Cl.
3. Alkyl chlorides (RCl) have the strongest C–Cl bond among these, making them the least reactive in nucleophilic substitution.

Hence, the reactivity decreases in the order RI > RBr > RCl.