Assertion (A): $(CH X_{3}) X_{3} C - Cl$ solvolyses much faster than $(CH X_{3}) X_{2} CH - Cl$ in 80% aqueous ethanol. Reason (R): Nucleophilic approach to the tertiary carbon is less hindered than approach to the secondary carbon.

ABoth A and R are true, and R is the correct explanation of A
BBoth A and R are true, but R is not the correct explanation of A
CA is true but R is false
DA is false but R is true

Answer: C

A is true: the tertiary halide gives the more stable tertiary carbocation (inductive effect and hyperconjugation), lowering the ionisation barrier. R is false: the tertiary carbon is more crowded, not less, and ease of approach is not the factor in a slow ionisation step.

Practice Organic Reaction Mechanisms III: Nucleophilic Substitution More on SN1 vs SN2: substrate, nucleophile, solvent, leaving group

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Assertion (A): (CHX3​)X3​C−Cl solvolyses much faster than (CHX3​)X2​CH−Cl in 80% aqueous ethanol. Reason (R): Nucleophilic approach to the tertiary carbon is less hindered than approach to the secondary carbon.

Answer: C

More questions on SN1 vs SN2: substrate, nucleophile, solvent, leaving group

Assertion (A): $(CH X_{3}) X_{3} C - Cl$ solvolyses much faster than $(CH X_{3}) X_{2} CH - Cl$ in 80% aqueous ethanol. Reason (R): Nucleophilic approach to the tertiary carbon is less hindered than approach to the secondary carbon.