Haloalkanes and Haloarenes — Class 12 MCQs with Answers
Class 12 CBSE Chemistry · Chapter 6
96 practice questions · 32 Easy · 32 Medium · 32 Hard · Updated
Practise the most important Class 12 CBSE Chemistry questions from Chapter 6, "Haloalkanes and Haloarenes". You get 9 timed quizzes made from 96 NCERT-based MCQs, with answers and explanations. The questions are split into 32 Easy, 32 Medium and 32 Hard. Warm up on the basics, then move on to the exam-level questions that set top scorers in CBSE & Maharashtra HSC Board exams, JEE Main, MHT-CET, JEE Advanced and NEET UG apart.
To score well in "Haloalkanes and Haloarenes", focus on reactions, key concepts and careful numericals. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This trains you to stay accurate under time pressure, as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Haloalkanes and Haloarenes, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 12 Chemistry mastery score. 14 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Key concepts: Haloalkanes and Haloarenes (Class 12 Chemistry)
Haloalkanes and Haloarenes covers halogen compounds on sp³ and aromatic carbon: their preparation, the SN1 (carbocation, racemisation) and SN2 (concerted, inversion) substitution mechanisms, E1/E2 elimination with Zaitsev's rule, the low reactivity of haloarenes, optical isomerism, and named reactions such as Wurtz, Fittig, Finkelstein and Swarts.
- Classification
- Halogen on sp³ carbon (haloalkanes, further 1°/2°/3°) or on an aromatic ring (haloarenes); allylic, benzylic and vinylic types differ sharply in reactivity.
- Nature of the C–X bond
- The C–X bond is polar (X more electronegative), so carbon is electrophilic; bond strength falls C–F > C–Cl > C–Br > C–I, making iodides the most reactive.
- SN2 mechanism
- One-step, bimolecular; the nucleophile attacks the carbon from the side opposite the leaving group, giving inversion. Fastest for 1° (least steric hindrance).
- SN1 mechanism
- Two-step, unimolecular; slow ionisation to a carbocation then fast nucleophile attack. Fastest for 3° (stable carbocation), favoured by polar protic solvents.
Haloalkanes and Haloarenes — important questions & MCQs with answers (Class 12 Chemistry)
14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 82 are timed and scored when you sign in.
- Q1Easy
General formula of haloalkanes:
A.CₙHₙXB.CₙH₂ₙXC.CₙH₂ₙ₊₁X✓ CorrectD.CₙHXAnswer: C. CₙH₂ₙ₊₁X
Explanation: Replacing one H of the alkane CₙH₂ₙ₊₂ with a halogen keeps the saturated skeleton, giving CₙH₂ₙ₊₁X — the CₙH₂ₙX distractor wrongly implies a degree of unsaturation.
- Q2Easy
Nucleophilic substitution involves:
A.Replacement of leaving group by nucleophile✓ CorrectB.Adding waterC.Heat onlyD.PolymerisationAnswer: A. Replacement of leaving group by nucleophile
Explanation: Nucleophilic substitution means an electron-rich nucleophile displaces the leaving group on carbon, e.g. OH⁻ replacing Br⁻ — a bond-breaking/bond-making swap, not simple heating or polymerisation.
- Q3Easy
What is the IUPAC name of CH₃CH₂CH₂Cl?
A.2-ChloropropaneB.1-Chloropropane✓ CorrectC.ChloropropeneD.Propyl chlorideAnswer: B. 1-Chloropropane
Explanation: Numbering the three-carbon chain to give the halogen the lowest locant puts Cl on C1, so CH₃CH₂CH₂Cl is 1-chloropropane — 2-chloropropane would need Cl on the middle carbon instead.
- Q4Easy
In CH₃Br + OH⁻ → CH₃OH + Br⁻, the nucleophile is:
A.CH₃⁺B.Br⁻C.OH⁻✓ CorrectD.H⁺Answer: C. OH⁻
Explanation: In CH₃Br + OH⁻ → CH₃OH + Br⁻, OH⁻ is the electron-pair donor that attacks carbon and displaces Br⁻, making it the nucleophile; Br⁻ is the leaving group, not the attacking species.
- Q5Easy
Identify the classification of (CH₃)₃CBr as a haloalkane.
A.VinylB.Secondary (2°)C.Primary (1°)D.Tertiary (3°)✓ CorrectAnswer: D. Tertiary (3°)
Explanation: The carbon bonded to Br in (CH₃)₃CBr is attached to three other carbons, the definition of a tertiary (3°) halide — a secondary halide needs exactly two carbon attachments at that carbon.
- Q6Easy
Which is the best leaving group among the following halides?
A.I⁻✓ CorrectB.Cl⁻C.Br⁻D.F⁻Answer: A. I⁻
Explanation: A good leaving group is the stable conjugate base of a strong acid; I⁻ is the largest, most polarizable, least basic halide ion, so C–I breaks most easily, making I⁻ the best leaving group here.
- Q7Medium
Sn1 leads to:
A.Racemic mixture from chiral substrate✓ CorrectB.Pure inversionC.No reactionD.PolymerAnswer: A. Racemic mixture from chiral substrate
Explanation: SN1 goes through a planar sp² carbocation that a nucleophile can attack from either face, so one enantiomer of R–X gives a racemic (50:50) mixture, not the clean inversion of SN2.
- Q8Medium
Sn2 reaction is:
A.Photochemical onlyB.Two-step via carbocationC.Free radicalD.Single-step concerted (bimolecular)✓ CorrectAnswer: D. Single-step concerted (bimolecular)
Explanation: SN2 is single-step and bimolecular: the nucleophile attacks the backside of C–X as the leaving group departs, so rate depends on both R–X and nucleophile — unlike the two-step carbocation route of SN1.
- Q9Medium
IUPAC name of (CH₃)₃CCH₂Br is:
A.1-Bromo-2,2-dimethylpropane✓ CorrectB.Neopentyl bromideC.tert-Butyl bromideD.2-Bromo-2-methylbutaneAnswer: A. 1-Bromo-2,2-dimethylpropane
Explanation: (CH₃)₃CCH₂Br has a central quaternary carbon bearing three methyls and a CH₂Br; taking CH₂Br–C–CH₃ as the three-carbon chain leaves two methyl substituents on C2, giving 1-bromo-2,2-dimethylpropane.
- Q10Medium
Which substrate would react fastest by SN2 mechanism?
A.(CH₃)₃CBrB.(CH₃)₂CHBrC.CH₃Br✓ CorrectD.C₆H₅BrAnswer: C. CH₃Br
Explanation: SN2 rate falls as alkyl substitution increases because bulky groups block backside attack on carbon; CH₃Br has no such crowding, so it reacts fastest, while C₆H₅Br (an aryl halide) doesn't undergo SN2 at all.
- Q11Medium
Preparation of CH₃CH₂Cl from CH₃CH₂OH uses:
A.NaOHB.HBr/H₂SO₄C.SOCl₂ (Darzen's procedure)✓ CorrectD.I₂/PAnswer: C. SOCl₂ (Darzen's procedure)
Explanation: SOCl₂ (Darzen's process) converts CH₃CH₂OH to CH₃CH₂Cl while releasing SO₂ and HCl as gases, leaving no residue behind — a cleaner route than HBr/H₂SO₄ or I₂/P, which leave inorganic byproducts.
- Q12Hard
Haloarenes are less reactive than haloalkanes in nucleophilic substitution because of:
A.Resonance and partial double-bond character of C–X✓ CorrectB.Higher massC.Higher temperatureD.No reasonAnswer: A. Resonance and partial double-bond character of C–X
Explanation: A lone pair on X conjugates into the ring, giving C–X partial double-bond character that shortens and strengthens the bond, so haloarenes resist the backside attack (SN2) that haloalkanes undergo easily.
- Q13Hard
E2 elimination requires:
A.AcidB.Weak base onlyC.Strong base, anti-periplanar H and leaving group✓ CorrectD.No baseAnswer: C. Strong base, anti-periplanar H and leaving group
Explanation: E2 is concerted: a strong base removes a β-hydrogen as the leaving group departs in one step, needing anti-periplanar (180°) alignment of H and the leaving group so their orbitals overlap as the π bond forms.
- Q14Hard
How many stereoisomers does 2,3-dibromobutane have?
A.2 (only enantiomers)B.3 (a pair of enantiomers + meso)✓ CorrectC.4 (all distinct)D.1Answer: B. 3 (a pair of enantiomers + meso)
Explanation: 2,3-Dibromobutane has two stereocentres; the (R,R) and (S,S) combinations are non-superimposable mirror images (enantiomers), while (R,S) has an internal mirror plane making it one achiral meso compound — three stereoisomers total.
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What are the key concepts in Class 12 Chemistry Haloalkanes and Haloarenes?+
Haloalkanes and Haloarenes covers halogen compounds on sp³ and aromatic carbon: their preparation, the SN1 (carbocation, racemisation) and SN2 (concerted, inversion) substitution mechanisms, E1/E2 elimination with Zaitsev's rule, the low reactivity of haloarenes, optical isomerism, and named reactions such as Wurtz, Fittig, Finkelstein and Swarts. Key ideas include Classification, Nature of the C–X bond, SN2 mechanism, SN1 mechanism.
What does Class 12 Chemistry Chapter 6 (Haloalkanes and Haloarenes) cover on XamBaaz?+
It has 96 NCERT-based MCQs on "Haloalkanes and Haloarenes": 32 Easy, 32 Medium and 32 Hard. Together they make 9 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE & Maharashtra HSC Board exams, JEE Main, MHT-CET, JEE Advanced and NEET UG.
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Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 9 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
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Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip, the same negative marking as JEE Main, JEE Advanced and NEET UG. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Haloalkanes and Haloarenes (Class 12 Chemistry)?+
The questions that matter most test Classification, Nature of the C–X bond, SN2 mechanism, SN1 mechanism. This page shows 14 solved important MCQs with answers and explanations; all 96 questions on the chapter are available as timed quizzes once you sign in.
Is there an online quiz for Haloalkanes and Haloarenes?+
Yes — Class 12 Chemistry Haloalkanes and Haloarenes has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.