Haloalkanes & Haloarenes: Class 12 Previous Year Questions

Haloalkanes & Haloarenes questions asked in CBSE board exams

Repeated questions first. Open the free app to see each question as it appeared in the paper, with its marking scheme.

1. Calculate emf of the following cell at 298 K : 3 Sn | Sn2+ (0.001 M) || H+ (0.01 M) | H2(g) (1 bar) | Pt(s) Given : Eo Sn2+/Sn = – 0.14 V, Eo H+/H2 = 0.00 V [log 10 = 1]
   Board 20263 marksshort answer
2. (a) Write the major product in the following reactions : 1 + 1 + 1 + Br2 heat  ? (b) Define Racemic mixture. (c) p-dichlorobenzene has a higher melting point as compared to its ortho and meta isomers. Why ?
   Board 20263 marksshort answer
3. (a) Draw the structure of the given compound : 1 + 1 4–Bromo–3–methylpent–2–ene (b) What happens when chloroethane is treated with aqueous potassium hydroxide ?
   Board 20262 marksshort answer
4. Which of the following molecules is chiral in nature ? 1 (A) Propan–2–ol (B) Butan–2–ol (C) 1–Bromobutane (D) 2–Bromopropane
   Board 20261 markMCQ
5. (a) In the following pair of halogen compounds, which compound undergoes Snl reaction faster and why ? CI and (b) Arrange the following compounds in increasing order of their reactivity towards Sn2 displacement : 2-Bromo-2-methylbutane, 1-Bromopentane, 2-Bromo…
   Board 20252 marksshort answer
6. Which is the correct IUPAC name for CH3 Cl Methylchlorobenzene (B) (A) Toluene (C)1-Chloro-4-Methylbenzene (D) 1-Methyl-4-Chlorobenzene
   Board 20251 markMCQ
7. (A) Draw the structure of the major monohalo product for each of the following reaction : (1 + 1 + 1 = 3) Br2, Heat (a) + HBr (b) CH3 HO HCl, Heat (c) HO -H, OR (B) How do you convert : (3 × 1 = 3) (a) Chlorobenzene to biphenyl (b) Propene to 1-Iodopropane (c)…
   Board 20253 marksshort answer
8. (a) Define the following : 2+1=3 (i) Enantiomers (ii) Racemic mixture (b) Why is chlorobenzene resistant to nucleophilic substitution reaction ? · 13 27. ·A· · 3×1 (a) ·hehe ·-hb (b) (c) : () 2 × 1% = 3 SOCl2 (a) CH,COOH 1.(DIBAL-H) HON EP CH,CN >B (b) 2. H20 …
   Board 20253 marksshort answer
9. Alkyl halides undergoing nucleophilic bimolecular substitution reaction involve (A) retention of configuration (B) formation of racemic mixture (C)i inversion of configuration (D) formation of carbocation
   Board 20251 markMCQ
10. Assertion (A) : The boiling points of alkyl halides decrease in the order : RI > RBr >RCl > RF. Reason (R) : The boiling points of alkyl chlorides, bromides and iodides are considerably higher than that of the hydrocarbon of comparable molecular mass.
    Board 20251 markAssertion-Reason
11. (a) In the following pair of compounds, which compound undergoes SN2 reaction faster and why ? (b) Write the major product in the following : 1+1=2
    Board 20242 marksshort answer
12. For the reaction X + 2Y P, the differential form equation of the rate law is : (A) 2d P d Y = dt dt (B) d P d X = dt dt (C) + d X d P = dt dt (D) 2d Y + d P = dt dt 6 6. dh `m¡{JH$ Omo SN1 A{^{H«$`m AË`{YH$ erK«Vm go H$aVm h¡, dh h¡ : 7. Eogr{Q>H$ Aåb PCl5 Ho$…
    Board 20241 markMCQ
13. Answer any 3 of the following : 3  1 (a) Which isomer of C5H10 gives a single monochloro compound C5H9Cl in bright sunlight ? (b) Arrange the following compounds in increasing order of reactivity towards SN2 reaction : 2-Bromopentane, 1-Bromopentane, 2-Bromo-…
    Board 20233 marksshort answer
14. The conversion of an alkyl halide into an alkene by alcoholic KOH is classified as 1 (a) a substitution reaction (b) an addition reaction (c) a dehydrohalogenation reaction (d) a dehydration reaction 4 2. [Fe(CO)5]  Fe     1 (a) + 2 (b) 0 (…
    Board 20231 markMCQ
15. Racemisation occurs in 1 (a) SN1 reaction (b) SN2 reaction (c) Neither SN1 nor SN2 reaction (d) SN2 reaction as well as SN1 reaction 6 7.   KH   1 (a)        (b)        (c)        (d) …
    Board 20231 markMCQ
16. Assertion (A) : Nucleophilic substitution of iodoethane is easier than chloroethane. 1 Reason (R) : Bond enthalpy of C-I bond is less than that of C-Cl bond.
    Board 20231 markAssertion-Reason
17. Given below are two statements labelled as Assertion (A) and Reason (R). Assertion (A): At a constant temperature, the dissociation constant of chloroethanoic acid will be higher than that of propanoic acid. Reason (R): Higher the number of carbon atoms in a c…
    CBSE practice 2022-231 markAssertion-Reason
18. Nucleophilic Substitution Reactions In nucleophilic substitution reactions, a bond between carbon and a leaving group (C–LG) is broken, and a new bond between carbon and a nucleophile (C–Nu) is formed. Nucleophilic substitution reactions of alkyl halides occur…
    CBSE practice 2023-244 markscase-based
19. Three sets of pairs (i) and (ii) of SN1 reactions are given below. For each set of reactions state which reaction (i) or (ii) is expected to be slower? Justify your answer. (a) (i) (CH3)3CCl + CH3CH2O- (CH3)3COCH2CH3 +Cl- [In presence of ethanol] (ii) (CH3)3CC…
    CBSE practice 2023-243 marksshort answer
20. 2-bromooctane reacts with alcoholic NaOH to give 2-octanol as shown below. (a) Identify the type of substitution reaction mechanism. Justify your answer. (b) What effect will it have on the rate of the reaction if: (i) the concentration of NaOH is reduced by h…
    CBSE practice 2022-232 marksshort answer

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