Read the statements related to the following reaction and choose the correct statements
(A) It is SN1 reaction
(B) This process follows inversion of configuration.
(C) It follows second order kinetics.
(D) It is SN2 reaction.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (B), (C) and (D) only
Nucleophilic substitution in alkyl halides follows one of two mechanisms. SN2 is a single step: the nucleophile attacks from the side opposite to the halogen, so the configuration is inverted, and Rate = k[RX][Nu−] (second order). SN1 goes through a carbocation in two steps, and Rate = k[RX] (first order).
The given figure shows backside attack of \( \ce{OH^{-}} \) on chloromethane through a single transition state, with inversion of the hydrogens. So the reaction is SN2.
(A) It is SN1 reaction — Incorrect. No carbocation is formed; the reaction goes through a single transition state.
(B) This process follows inversion of configuration. — Correct. Backside attack inverts the configuration, like an umbrella turned inside out.
(C) It follows second order kinetics. — Correct. Both reactants take part in the only step:
\( \displaystyle \text{Rate}=k[\ce{CH3Cl}][\ce{OH^-}] \)
(D) It is SN2 reaction. — Correct. A single-step, bimolecular substitution is SN2.
NCERT (2026-27 edition):
Substitution Nucleophilic Bimolecular (SN2)
Substitution Nucleophilic Bimolecular (SN2) – “… As the reaction progresses and the bond between the incoming nucleophile and the carbon atom starts forming, the bond between carbon atom and leaving group weakens. … As a result configuration is inverted, the configuration of carbon atom under attack inverts in much the same way as an umbrella is turned inside out when caught in a strong wind. This process is called as inversion of configuration.”