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Free Alkyl Halides MCQs with Answers

458 Alkyl Halides MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

Alkyl halides are named and related to their carbon-halogen structure, polarity and reactivity. The key reactions are nucleophilic substitution by SN1 and SN2 mechanisms and elimination by E1 and E2 mechanisms, including how substrate structure, nucleophile, base, solvent and temperature influence substitution versus elimination.

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Nomenclature, Structure and ReactivityNucleophilic SubstitutionElimination Reactions
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458 questions · page 19 of 23

361. Directions: In the following question, a number sequence is given with one term missing. Choose the correct term that will continue the same pattern and replace the question mark in the given sequence.

  • A. 21/43
  • B. 43/21
  • C. 17/35
  • D. 20/41

Explanation: The correct answer is 21/43. To find this, observe the patterns separately in numerators and denominators:Numerators:1, 3, 6, 10, 15 -…

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Correct answer: 21/43

362. Directions: Read the following information and give answer.A, B. C, D and E are five friends. B is elder to E, but not as tall as C. C is younger to A. and is taller to D and E. A is taller to D, but younger than E. D is elder to A but is shortest in the group.Which of the following pairs of students is elder to D?

  • A. BA
  • B. BC
  • C. BE
  • D. None of these

Explanation: To solve the problem, we need to deduce the chronological order of the friends' ages based on the given clues:1. B is elder to E.2.

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Correct answer: BE

363. In the following question, two statements numbered I and II are given. There may be cause and effect relationship between the two statements. These two statements may be the effect of the same cause or independent causes. These statements may be independent causes without saving any relationship. Read both the statements in question and mark your answer as:A. If statement I is the cause and statement II is its effect;B. If statement II is the cause and statement, I is its effect;C. If both the statements I and II are independent causes;D. If both the statements I and II are effects of independent causes;E. If both the statements I and II are effects of some common causes;I. Heavy rains totally flooded the area.II. Residents of the area have been moved temporarily to other parts of the city.

  • A. If statement I is the cause and statement II is its effect;
  • B. If statement II is the cause and statement I is its effect;
  • C. If both the statements I and II are independent causes;
  • D. If both the statements I and II are effects of independent causes;
  • E. If both the statements I and II are effects of some common cause;

Explanation: The correct answer is Option A. Statement I describes heavy rains that have resulted in flooding, a condition that typically necessitates…

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Correct answer: If statement I is the cause and statement II is its effect;

364. In this question, a statement is given followed by two courses of action numbered I and II. It is required to grasp the statement, analyze the problem or policy it mentions and then decide which of the courses of action logically follow / most appropriate.Statement:The Govenment has decided not to provide financial support to voluntary organizations from next five-year plan and has communicated that all such organizations should raise funds to meet their financial needs.Courses of action:I) Voluntary organizations should collaborate with foreign agencies.II) They should explore other sources of financial support.

  • A. If only I follows
  • B. If only II follows
  • C. If either I or II follows
  • D. If neither I nor II follows
  • E. If both I and II follow

Explanation: The correct answer is Option B: If only II follows. The statement indicates that the government will no longer provide financial support…

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Correct answer: If only II follows

365. Which of the following base will favour substitution reaction as compared to the elimination reaction?

  • A. ŌH
  • B. ŌR
  • C. NH2
  • D. I-1

Explanation: NH2 (amine) is correct because it is a weaker base compared to hydroxide ion and alkoxide ions, favoring substitution reactions over…

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Correct answer: NH2

366. Predict the product of reaction:

  • A. CH3 - NH2
  • B. CH3 - CH2 -NH2
  • C. OH|CH3 - CH - CH3
  • D. O||CH3 - C - OH

Explanation: Ethylamine is the correct product of the reduction of acetamides. Acetamides, when reduced, undergo cleavage of the amide bond to form a…

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Correct answer: CH3 - CH2 -NH2

367. Propose which one of the following reactions is more likely to occur through SN1 mechanism?

  • A. (CH3)2CH − Cl CCl4/NaOH→ CH2)2 CH − OH
  • B. C2H5Cl NaOH/H2O→ C2H5 − OH
  • C. (CH3)3 CCl H2ONaOH→ (CH3)3C − OH
  • D. (CH3)3C − Cl CCl4/NaOH → (CH3)3COH

Explanation: This reaction is more likely to proceed through SN1 mechanism because generally, tertiary alkyl halides are more reactive through this…

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Correct answer: (CH3)3C − Cl CCl4/NaOH → (CH3)3COH

368. A compound X undergoes the following reactions:X NaOH(aq)/heat > C4H10O Cr2O7(2-), H+(aq)/ heat> C4H8O.What is X?

  • A. 1 - Bromobutane
  • B. 2 - Bromobutane
  • C. 1-Bromo-2-Methylpropane
  • D. 2 - Bromo - 2 - Methylpropane

Explanation: C4H8O having one oxygen rules out the possibility of the intermediate compound being a primary alcohol as if it were to be a primary…

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Correct answer: 2 - Bromobutane

369. What is true about the mechanisms I and II

  • A. Both are SN1
  • B. (I) is SN1, (II) is SN2
  • C. Both are SN2
  • D. (I) is SN2, (II) is SN1

Explanation: In mechanism I, the reaction follows an SN2 pathway. This involves a single concerted step where the nucleophile attacks the substrate…

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Correct answer: (I) is SN2, (II) is SN1

370. Which of the following intermediate has the complete octet around the carbon atom?

  • A. Free radical
  • B. Carbanion
  • C. Carbonium ion
  • D. None of these

Explanation: In a carbanion carbon is bonded to three atoms or groups (trivalent) and has eight electrons(octet). It is an electron rich species.

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Correct answer: Carbanion

371. The rate of SN2 reaction becomes doubled if the _.

  • A. Concentration of nucleophile doubled
  • B. Concentration of substrate doubled
  • C. Concentration of substrate tripled
  • D. Concentration of substrate remains same

Explanation: The rate of SN2 reaction becomes doubled if the concentration of substrate is doubled.

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Correct answer: Concentration of substrate doubled

372. SN1 reaction is a _ ?

  • A. Multistep reaction
  • B. Two step reaction
  • C. Concerted reaction
  • D. 3 step reaction

Explanation: SN1 (Substitution Nucleophilic Unimolecular) is a type of nucleophilic substitution reaction mechanism in organic chemistry, which…

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Correct answer: Two step reaction

373. SN2 reactions are _ ?

  • A. 2 step reactions
  • B. Multistep reactions
  • C. Single-step reactions
  • D. None of these

Explanation: SN2 reactions are single-step reactions. This means that the bond breaking and bond forming steps happen at the same time.

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Correct answer: Single-step reactions

374. Alkyl iodides cannot be prepared directly by the halogenation of alkanes because _.

  • A. Iodine reacts slowly
  • B. Iodine reacts reversibly
  • C. The hydrogen iodide formed reduces the alkyl iodide to its starting material
  • D. All of these options are correct

Explanation: Option A: Iodine is slightly soluble in water. It has the lowest standard reduction potential of the halogens, and is therefore the least…

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Correct answer: All of these options are correct

375. SN1 reaction is a _.

  • A. Multi-step reaction
  • B. Two-step reaction
  • C. Concerted reaction
  • D. Three-step reaction

Explanation: The SN1 reaction is a nucleophilic substitution reaction where the rate-determining step is unimolecular.

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Correct answer: Two-step reaction

376. In which phase SN2 reactions are favored?

  • A. Solid
  • B. Liquid
  • C. Gas
  • D. All of these

Explanation: SN1 reactions are favoured in polar protic solvent i.e.,the solvents that can form hydrogen bonds.This is because the large dipole moment…

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Correct answer: Gas

377. Reduction of alkyl halides in the presence of Zn and mineral acid produces _ ?

  • A. Alkenes
  • B. Alkane
  • C. Alkynes
  • D. Alcohols

Explanation: Option B is correct as zinc carries out reductive dehalogenation of "alkyl halides" in which the halogen atom is replaced by a hydrogen…

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Correct answer: Alkane

378. SN1 reactions have which of the following species formed and consumed in the reaction?

  • A. Transition state
  • B. Intermediate
  • C. Carbanion
  • D. Carbene

Explanation: Option B is correct since SN1 reactions involve two steps and in the first step, carbonium ion form is positive.

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Correct answer: Intermediate

379. Which of the following bond has highest bond energy value ?

  • A. C-I
  • B. C-H
  • C. C-Cl
  • D. C-F

Explanation: Fluorine has the highest bond energy because it has the smallest atomic radius and the highest electronegativity of all the halogens.

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Correct answer: C-F

380. In a reaction having both alkyl halide and base, the base will attack on _.

  • A. Electrophilic carbon
  • B. Nucleophilic carbon
  • C. Beta-hydrogen
  • D. None of these options is correct

Explanation: Chlorides generally give more elimination reactions than iodides, since the greater electronegativity of chlorine increases the acidity of…

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Correct answer: Beta-hydrogen
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