NEET (UG) · Chemistry, Class 12
Haloalkanes and Haloarenes: NEET PYQ, 2018–2026
Haloalkanes and Haloarenes (Chemistry, Class 12) has been asked 9 times in the 7 NEET papers from 2018, 2020, 2021, 2023, 2024, 2025 and 2026: about 1.3 questions a paper, 3% of all Chemistry questions. It is the 19th most-asked of 21 Chemistry chapters. NEET 2026 had 0 from it. Last checked 28 October 2026.
Questions per paper
Year by year.
| Year | Questions |
|---|---|
| 2018 | 0 |
| 2020 | 1 |
| 2021 | 2 |
| 2023 | 3 |
| 2024 | 2 |
| 2025 | 1 |
| 2026 | 0 |
From 2021 to 2024 each paper had 200 questions (a Section B with a choice); the others had 180.
Inside the chapter
Topics asked most.
- Elimination reactions3
- Nature of the C–X bond3
- SN1 and SN2 mechanisms3
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10 Haloalkanes and Haloarenes questions to practise.
Our own questions, written in the NEET pattern and checked, each with an explanation. Pick an option to see the answer.
Q1 · Chemistry · Haloalkanes and Haloarenes
Chlorofluorocarbons (freons) are harmful to the environment mainly because they:
Answer: (A)
Freons are unreactive near the ground and drift up to the stratosphere, where ultraviolet radiation breaks them down to chlorine radicals. Each radical starts a chain reaction that destroys many ozone molecules.
Q2 · Chemistry · Haloalkanes and Haloarenes
In electrophilic substitution, the chlorine atom of chlorobenzene:
Answer: (D)
Chlorine withdraws electrons by its −I effect, which deactivates the ring, so substitution is slower than in benzene. But its lone pairs, by resonance, raise the electron density at the ortho and para positions, so the incoming group goes there.
Q3 · Chemistry · Haloalkanes and Haloarenes
2-Bromo-1-phenylpropane (C₆H₅CH₂CHBrCH₃) is heated with alcoholic KOH. Which statement describes the main product correctly?
Answer: (A)
Dehydrohalogenation removes HBr, with H lost from a β-carbon. Here there are two β-carbons. The CH₃ carbon gives C₆H₅CH₂CH=CH₂, which is non-conjugated and monosubstituted. The benzylic CH₂ carbon gives C₆H₅CH=CHCH₃, which is disubstituted and conjugated with the aromatic ring. By Zaitsev's rule, with extra stabilisation from conjugation, the second alkene is the major product (mainly the trans isomer). Alcoholic KOH is not a bulky base, so the Hofmann product is not favoured, and the medium favours elimination over substitution.
Q4 · Chemistry · Haloalkanes and Haloarenes
Polychlorinated biphenyls (PCBs), once used as coolants and insulating fluids, are persistent pollutants. Which property of PCB molecules mainly causes them to accumulate in the fatty tissues of organisms and increase in concentration at higher trophic levels?
Answer: (A)
Principle: persistent organic pollutants such as PCBs are non-polar and lipophilic (fat-soluble). Because they are not readily broken down or excreted, they are stored in the fatty tissue of organisms. When a predator eats many contaminated prey, the pollutant accumulates in its body, so its concentration rises at each higher trophic level. This is biomagnification. The key property is lipid solubility, not volatility, water solubility or ionic character. The question is answered by recalling that the compounds are non-polar and fat-soluble.
Q5 · Chemistry · Haloalkanes and Haloarenes
The C–Cl bond length in chloromethane is 178 pm and its dipole moment is 1.86 D. Treat the entire dipole moment as arising from the C–Cl bond, and assume the bond consists of charges +δ on carbon and –δ on chlorine separated by 178 pm. What is δ, as a multiple of the electronic charge e? (1 D = 3.336 × 10⁻³⁰ C m, e = 1.602 × 10⁻¹⁹ C)
Answer: (A)
Dipole moment μ = charge × distance = δe × d. Convert μ to SI units: 1.86 D = 1.86 × 3.336 × 10⁻³⁰ C m = 6.21 × 10⁻³⁰ C m. Then e·d = 1.602 × 10⁻¹⁹ C × 1.78 × 10⁻¹⁰ m = 2.85 × 10⁻²⁹ C m. So δ = 6.21 × 10⁻³⁰ / 2.85 × 10⁻²⁹ ≈ 0.22. The C–Cl bond is therefore polar covalent and not ionic, with about 0.22 e of charge displaced from C to Cl.
Q6 · Chemistry · Haloalkanes and Haloarenes
A sample of 11.95 g of chloroform (M = 119.5 g/mol) is kept in a clear, partly filled bottle in sunlight. Over time 30% of the chloroform is oxidised by atmospheric oxygen according to 2CHCl3 + O2 → 2COCl2 + 2HCl. What mass of phosgene (COCl2, M = 99 g/mol) is formed, and how many moles of O2 are consumed?
Answer: (A)
Principle: use the balanced equation 2CHCl3 + O2 → 2COCl2 + 2HCl and convert mass to moles and back with the right molar mass. Application: n(CHCl3) = 11.95/119.5 = 0.100 mol, and 30% of it is 0.030 mol. The ratio CHCl3 : COCl2 is 1:1, so n(COCl2) = 0.030 mol and its mass is 0.030 × 99 = 2.97 g. The ratio CHCl3 : O2 is 2:1, so n(O2) = 0.015 mol. This slow air oxidation in light, which also releases HCl, is why chloroform is stored in dark, completely filled bottles with no air space.
Q7 · Chemistry · Haloalkanes and Haloarenes
Which carbon-halogen bond in a haloalkane (CH3-X) is the longest?
Answer: (D)
Bond length depends on the sum of the covalent radii of carbon and the halogen. Because the halogen radius increases going down the group from F to I, the bond length increases in the order C-F < C-Cl < C-Br < C-I. Hence the C-I bond is the longest.
Q8 · Chemistry · Haloalkanes and Haloarenes
Laboratory chloroform is stored in dark brown bottles that are filled to the brim and closed tightly. Which of the following gives the correct reason for this practice?
Answer: (A)
Principle: chloroform is slowly oxidised by atmospheric oxygen in the presence of light to carbonyl chloride (COCl2, phosgene), 2CHCl3 + O2 → 2COCl2 + 2HCl. Phosgene is a highly poisonous gas. Application: to stop this reaction, both light and oxygen must be removed. Dark brown bottles cut off light, and filling the bottle to the brim leaves almost no air. The other options either confuse chloroform with CCl4, treat the practice as purely physical, or propose a hydrolysis reaction that is not the hazard.
Q9 · Chemistry · Haloalkanes and Haloarenes
Chloromethane has a dipole moment of 1.86 D and a C–Cl bond length of 178 pm. Assume the whole dipole moment arises from the C–Cl bond, treated as point charges +δe and −δe separated by the bond length. Use 1 D = 3.34 × 10⁻³⁰ C m and e = 1.60 × 10⁻¹⁹ C. What is the magnitude of the fractional charge δ on the chlorine atom?
Answer: (A)
A bond dipole moment is μ = q × d, where q is the charge on each end and d is the separation between the charges. Here q = δe. Convert the units first: μ = 1.86 × 3.34 × 10⁻³⁰ = 6.21 × 10⁻³⁰ C m, and d = 178 pm = 1.78 × 10⁻¹⁰ m. Then q = 6.21 × 10⁻³⁰ / 1.78 × 10⁻¹⁰ = 3.49 × 10⁻²⁰ C, so δ = 3.49 × 10⁻²⁰ / 1.60 × 10⁻¹⁹ ≈ 0.22. The C–Cl bond is therefore about 22% ionic, polar covalent and nowhere near fully ionic. The chlorine carries a partial negative charge and the carbon a partial positive charge. The common errors are halving the charge, halving the distance, and slipping a power of ten in the picometre conversion.
Q10 · Chemistry · Haloalkanes and Haloarenes
The increase in concentration of a non-biodegradable pesticide at successively higher levels of a food chain is called what?
Answer: (A)
Non-biodegradable chemicals are not broken down or excreted quickly, so they are retained in body fat. Each predator eats many prey, so the chemical's concentration grows at each higher trophic level. This process is called biomagnification. Students may confuse it with eutrophication, which concerns nutrient enrichment of water rather than food-chain transfer.
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All 9 real NEET questions from Haloalkanes and Haloarenes.
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About Haloalkanes and Haloarenes in NEET.
How many questions come from Haloalkanes and Haloarenes in NEET?
Haloalkanes and Haloarenes (Chemistry, Class 12) has been asked 9 times in the 7 NEET papers from 2018, 2020, 2021, 2023, 2024, 2025 and 2026: about 1.3 questions a paper, 3% of all Chemistry questions. It is the 19th most-asked of 21 Chemistry chapters. NEET 2026 had 0 from it.
Which topics of Haloalkanes and Haloarenes are asked most in NEET?
Elimination reactions (3), Nature of the C–X bond (3), SN1 and SN2 mechanisms (3), counted over the papers from 2018–2026.
Is Haloalkanes and Haloarenes important for NEET 2027?
It is in the syllabus in force, so it can be asked. By past papers it ranks 19 of 21 in Chemistry; use that to decide how much time it gets, not whether to study it.
Where can I solve Haloalkanes and Haloarenes NEET previous year questions?
On Nikaalle, free: sign up and practise every past NEET question from Haloalkanes and Haloarenes with an explanation for each, or sit the full papers timed. The ten questions on this page are our own, written in the same pattern.
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