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Rajasthan Board Class 12 (RBSE) Haloalkanes and Haloarenes — practice questions

Explore 16 free Haloalkanes and Haloarenes questions in Rajasthan Board Class 12 (RBSE) Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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Haloalkanes and Haloarenes questions and exercises with answers

Showing questions 1–16 of 16.

Haloalkanes are compounds derived from alkanes byRead the answer and worked solution →$\mathrm{(CH_3)_3CCl}$ is classified as aRead the answer and worked solution →The reactivity order for the $\mathrm{S_N 1}$ mechanism among haloalkanes isRead the answer and worked solution →The WURTZ REACTION couples two alkyl halides with sodium metal in dry ether to giveRead the answer and worked solution →The reactivity of haloalkanes toward nucleophilic substitution generally follows the orderRead the answer and worked solution →A SN2 reaction on a chiral carbon (with a single stereocentre) results inRead the answer and worked solution →The IUPAC name of $\mathrm{(CH_3)_2CH{-}CH_2Br}$ isRead the answer and worked solution →A GRIGNARD REAGENT is formed by reacting an alkyl halide withRead the answer and worked solution →NEET · Chemistry · SN1 or SN2Read the answer and worked solution →Fix the wrong word on halide reactionsRead the answer and worked solution →Sort each clue into SN1 or SN2Read the answer and worked solution →Match each named reactionRead the answer and worked solution →Sort the SN1 and SN2 traitsRead the answer and worked solution →Swipe by the carbon holding XRead the answer and worked solution →Spot the false claimRead the answer and worked solution →Pick the bigger halide valueRead the answer and worked solution →

Worked practice questions

Haloalkanes are compounds derived from alkanes by

  1. replacing one or more hydrogen atoms with halogen atoms
  2. adding $\mathrm{OH}$ groups to the chain
  3. removing the terminal carbon
  4. converting all C-H bonds to C-O bonds
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Correct answer: A. replacing one or more hydrogen atoms with halogen atoms

1. Your syllabus: a haloalkane (alkyl halide) is an alkane in which one or more H atoms have been replaced by HALOGEN atoms (F, Cl, Br, or I). 2. General formula for monohaloalkanes: $\mathrm{C_nH_{2n+1}X}$, where X is the halogen. 3. Examples: $\mathrm{CH_3Cl}$ (chloromethane), $\mathrm{CH_3CH_2Br}$ (bromoethane), $\mathrm{(CH_3)_3CCl}$ (tert-butyl chloride). 4. Distinct from haloarenes (where the halogen is attached to an aromatic ring — e.g. $\mathrm{C_6H_5Cl}$ chlorobenzene). 5. Options B (alcohols), C (chain shortening), D (over-oxidation) describe different transformations. _Source: syllabus Chemistry Part 2, Ch 6 "Haloalkanes and Haloarenes", §6.1 (Classification), p. 1._

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$\mathrm{(CH_3)_3CCl}$ is classified as a

  1. primary (1°) haloalkane
  2. secondary (2°) haloalkane
  3. tertiary (3°) haloalkane
  4. vinyl halide
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Correct answer: C. tertiary (3°) haloalkane

1. Your syllabus: haloalkanes are classified by the type of carbon bearing the halogen. 2. PRIMARY: the carbon attached to halogen is connected to ONE other carbon. SECONDARY: two. TERTIARY: three. 3. In $\mathrm{(CH_3)_3CCl}$, the C bonded to Cl is connected to THREE other carbons (three methyl groups). 4. So this is a TERTIARY (3°) haloalkane. Common name: tert-butyl chloride; IUPAC: 2-chloro-2-methylpropane. 5. Tertiary haloalkanes favour SN1 mechanisms (stable tertiary carbocations). 6. Options A and B are wrong substitution counts. Option D requires C=C adjacent to the halogen, not present here. _Source: syllabus Chemistry Part 2, Ch 6, §6.1 (Classification — 1°/2°/3°), p. 1–2._

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The reactivity order for the $\mathrm{S_N 1}$ mechanism among haloalkanes is

  1. 1° > 2° > 3°
  2. 3° > 2° > 1° > methyl
  3. methyl > 1° > 2° > 3°
  4. all classes react at the same rate
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Correct answer: B. 3° > 2° > 1° > methyl

1. SN1 mechanism: TWO-step process. Step 1: loss of leaving group → carbocation. Step 2: nucleophile attacks the carbocation. 2. The RATE-DETERMINING step is step 1 (carbocation formation). So the rate depends ONLY on the alkyl halide concentration (first-order kinetics) and on the STABILITY of the carbocation intermediate. 3. Carbocation stability order: TERTIARY > SECONDARY > PRIMARY > methyl (alkyl groups STABILISE the positive charge by hyperconjugation and induction). 4. So SN1 reactivity follows the same order: 3° > 2° > 1° > methyl. 5. This is the OPPOSITE order from SN2 (steric vs cation-stability factors). 6. Option A reverses the order. Option C is the SN2 order. Option D ignores the carbocation stability. _Source: syllabus Chemistry Part 2, Ch 6, §6.5.1 (SN1 mechanism — carbocation stability), p. 12._

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More Chemistry topics

Coordination CompoundsNamed ReactionsAlcohols Phenols EthersChemical KineticsSolid StateAlkenesAtomic combinationsAtoms and Elements