NEET-UG and JEE Main Chemistry · Class 12
SN1 and SN2 mechanisms — NEET & JEE Questions
SN1 and SN2 mechanisms is a topic in Organic Compounds Containing Halogens, a Class 12 Chemistry chapter of the NEET-UG and JEE Main syllabus. TestBudy holds 12 published NEET-UG and JEE Main questions on SN1 and SN2 mechanisms, each with the marking scheme of the real paper.
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SN1 and SN2 mechanisms MCQs with solutions
10 of the 12 published questions on this topic, exactly as they appear in a test. Answers and worked solutions come with your result rather than on this page.
An SN2 reaction proceeds through
- A. a single concerted step
- B. a carbocation intermediate
- C. a free-radical chain
- D. two carbocation intermediates
An SN1 reaction typically involves
- A. formation of a carbocation intermediate
- B. a single backside-attack transition state only
- C. no bond breaking
- D. a radical intermediate
The rate law for a simple SN1 reaction is generally
- A. rate = k[substrate]
- B. rate = k[substrate][nucleophile]
- C. rate = k[nucleophile] only
- D. rate independent of substrate
The rate law for a simple SN2 reaction is generally
- A. rate = k[substrate][nucleophile]
- B. rate = k[substrate] only
- C. rate = k[nucleophile] only
- D. rate = constant
Which substrate generally favours SN1 most strongly?
- A. Tertiary alkyl halide
- B. Methyl halide
- C. Primary alkyl halide
- D. Vinyl halide
Which substrate generally favours SN2 most strongly?
- A. Methyl halide
- B. Tertiary alkyl halide
- C. Highly hindered substrate
- D. A substrate requiring a stable tertiary carbocation
An SN2 reaction at a chiral carbon typically gives
- A. inversion of configuration
- B. complete retention only
- C. racemisation through a planar carbocation
- D. no stereochemical consequence
Why can an SN1 reaction at a chiral centre lead to racemisation?
- A. The planar carbocation can be attacked from either face
- B. Backside attack is compulsory
- C. No intermediate is formed
- D. The nucleophile cannot approach the carbocation
Which set of conditions most strongly favours SN2?
- A. Primary substrate, strong nucleophile, low steric hindrance
- B. Tertiary substrate, weak nucleophile, highly ionising solvent
- C. Stable tertiary carbocation formation
- D. Very hindered nucleophile and substrate
Which set of conditions most strongly favours SN1?
- A. Tertiary substrate in a polar protic medium
- B. Methyl substrate with strong nucleophile
- C. Primary substrate with no carbocation stabilisation
- D. A substrate that cannot ionise
Common mistakes in SN1 and SN2 mechanisms
Recorded against questions in this topic that are not shown above, so none of these points at an answer you can see on this page.
- Uses only substrate structure and ignores kinetic evidence.
- Uses only one clue and ignores the combined kinetic, structural and stereochemical evidence.
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