Given below are two statements:
Statement I: The conversion proceeds well in the less polar medium.
CH₃-CH₂-CH₂-CH₂-Cl →(HO⁻) CH₃-CH₂-CH₂-CH₂-OH+Cl⁽⁻⁾
Statement II: The conversion proceeds well in the more polar medium.
CH₃-CH₂-CH₂-CH₂-Cl→(R₃N̈)CH₃-CH₂-CH₂-CH₂-N(|(R))⁽⁺⁾-R Cl⁽⁻⁾
In the light of the above statements, choose the correct answer from the options given below

Solution

Chemistry ma’am · 4 steps

Do not just ask which solvent is polar; ask whether charge is created or spread out on the way to the TS.

1. Both are SN2. 1-Chlorobutane is a primary halide, so both reactions go by SN2 through one transition state. A polar solvent speeds up a step only if that transition state is more charged than the reactants, because the solvent then stabilises it more.

   Reaction	Reactants	Transition state	More polar solvent
   I: HO⁻ + C₄H₉Cl	full charge on HO⁻	[HO^(δ-)… C … Cl^(δ-)], same charge spread out	stabilises reactants more, slows it
   II: R₃N + C₄H₉Cl	both neutral	[R₃N^(δ+)… C … Cl^(δ-)], charges created	stabilises TS more, speeds it

2. Statement I. The charged HO⁻ is held tightly by a polar solvent, and the transition state is less concentrated in charge. A polar solvent lowers the reactants more than the TS, so the barrier rises. A less polar medium suits this reaction, so Statement I is true.
3. Statement II. Two neutral molecules come together to form an ion pair, R₃N⁺C₄H₉ Cl⁻. Charge separation builds up in the TS, and a more polar medium stabilises it, so Statement II is true.
4. So. Both statements are true, which is option (d).

The idea to keep. Compare the charge on the reactants with the charge on the transition state. Charge created: polar solvent helps. Charge spread out or destroyed: polar solvent hinders.

Answer from the NTA final answer key. Solution by PrepWiser.