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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Read the Alkyl Halides notesFree MDCAT chapter notes with key terms458 questions · page 16 of 23
- A. 4<3<2<1
- B. 1<3<2<4
- C. 1<2<3<4
- D. 1<2<4<3
Explanation: Correct Option:The correct increasing order of reactivity in SN reactions is B) 1<3<2<4.
Correct answer: 1<3<2<4302. The organic chloro compound which shows complete stereo chemical inversion during SN2 reaction is:
- A. (C2H5)2 CHCI
- B. (CH3)3CCI
- C. (CH3)2CHCI
- D. CH3-CI
Explanation: CH3Cl gives only SN2 reaction giving complete inversion.The correct option is D) CH3-Cl.
Correct answer: CH3-CI- A. E1 + SN1
- B. E2 + SN1
- C. SN1 + SN2
- D. None of these
Explanation: First step is same in SN1 and E2 i.e. ionization to form carbocation. While 2nd step is different in all SNI, SN2, E1 and E2.
Correct answer: None of these- A. Secondary
- B. Primary
- C. Teritary
- D. All have same stability
Explanation: Order of stability of carbocations: Tertiary>Secondary>Primary Stability of R+ ∞ Number of β-hydrogens ∞ Inductive effect The correct…
Correct answer: Teritary- A. NH3
- B. HBr
- C. Br2
- D. BH3
Explanation: NH3 has a lone pair to donate which makes it a good nucleophile.Correct Option:The correct option for the best nucleophile among the given…
Correct answer: NH3- A. CH3CH2-NH2
- B. CH3-CH2-H
- C. CH2-CH2
- D. CH3-CH2-CH3
Explanation: The correct option representing the product formed in the reaction is A) CH3CH2-NH2 (ethylamine).
Correct answer: CH3CH2-NH2- A. C-Br
- B. C-F
- C. C-CI
- D. C-I
Explanation: The correct option for the C-X bond with the highest bond energy per mole is B) C-F.
Correct answer: C-F- A. Concentration of nucleophile
- B. Concentration of substrate as well as alkyl halide
- C. Concentration of substrate only
- D. None of these
Explanation: For E1 reaction: R = K[R-X] (unimolecular mechanism). Therefore, option c is correct.
Correct answer: Concentration of substrate only- A. Addition
- B. Rearrangement
- C. Substitution
- D. Elimination
Explanation: In a substitution reaction, an atom or a group of atoms in a molecule is replaced by another atom or group of atoms.
Correct answer: Substitution- A. CN:
- B. :NH3
- C. CI-
- D. C2H5O-
Explanation: NH3 has no net charge so, is neutral. It is nucleophile due to presence of lone pair on nitrogen atom. Therefore, option b is correct.
Correct answer: :NH3311. CH3CH2-Br + CN- →?
- A. CH3CH2-Br
- B. CH2 = CH2
- C. CH3CH2-CN
- D. No reaction take place
Explanation: This is nucleophilic substitution reaction, Br is substituted by CN producing CH3CH2CN. Therefore, option c is correct.
Correct answer: CH3CH2-CN- A. 1o alkyl halides
- B. 2o alkyl halides
- C. 3o alkyl halide
- D. 4o alkyl halides
Explanation: In secondary alkyl halides, the halogen is attached to a carbon which is further attached to 2 carbon atoms. Therefore, option b is correct.
Correct answer: 2o alkyl halides313. Consider the following structural formula of alkyl halide: The correct name according to IUPAC is:
- A. 1-Bromo-4-methylpentane
- B. 2-Methyl-3-bromopentane
- C. 2-Methyl-1-bromopentane
- D. 2-Methyl-2-bromopentane
Explanation: The longest chain has 5 carbon atoms so, is a pentane (there are no double bonds).
Correct answer: 1-Bromo-4-methylpentane- A. The reaction of alcohol with HCI in the presence of catalyst ZnCl2
- B. The reaction of alcohol with PCI5
- C. The reaction of alcohol with PCI3
- D. The reaction of alcohol with SOCl2 in the presence of a pyridine solvent
Explanation: This method is commonly used to convert alcohols into alkyl chlorides and is known as Darzen's method.
Correct answer: The reaction of alcohol with SOCl2 in the presence of a pyridine solvent- A. R - CI
- B. R - Br
- C. R - I
- D. R - F
Explanation: Alkyl iodides can't be prepared by direct halogenation of alkanes because iodine is a weaker halogen compared to chlorine, bromine, and…
Correct answer: R - I- A. NH2-
- B. HSO4-
- C. OR-
- D. OH-
Explanation: This is the best-leaving group among the options given. When NH2- leaves a reaction intermediate, it becomes neutral ammonia (NH3), which…
Correct answer: NH2-- A. It is a bimolecular, 2nd order reaction
- B. Order of ease of SN2 mechanism in alkyl halide is 10 alkyl halide > 2o alkyl halide > 30 alkyl halide
- C. It takes place in the presence of a polar solvent
- D. It involves 100% inversion in the products
Explanation: In a polar solvent, the nucleophile is more solvated, leading to a decrease in the mobility and reactivity of the nucleophile.
Correct answer: It takes place in the presence of a polar solvent- A. Boiling points of haloalkanes are greater than that of alkanes
- B. Order of decreasing boiling points in alkyl halides is R - I > R - Br > R - CI > R - F
- C. Alkyl halides are soluble in water
- D. Primary alkyl halides can be prepared by reaction of PCI5 or SOCl2 with alcohols but not aryl halide
Explanation: Alkyl halides are not soluble in water. They are only slightly soluble in water, at best.
Correct answer: Alkyl halides are soluble in water- A. I-
- B. Cl-
- C. F-
- D. Br-
Explanation: Iodide ion (I⁻) is a good nucleophile and a good leaving group. This is because it is the largest of the halide ions, which means that it…
Correct answer: I-- A. 4-Methyl-6-chloroheptane
- B. 2-Chloro-4-methylheptane
- C. 2-Chloro-4-n-propythexane
- D. 2-Chloro-4-n-propylpentane
Explanation: The prefix "2-chloro" indicates that the chlorine atom is attached to the second carbon atom from the end of the chain.The prefix…
Correct answer: 2-Chloro-4-methylheptane