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 15 of 23
- A. HSO4-
- B. Cl-
- C. OH-
- D. Br-
Explanation: Option C is correct.OH- is not a good leaving group. A good leaving group is an ion that can easily leave a molecule without causing much…
Correct answer: OH-- A. 1
- B. 1.5
- C. 2
- D. 3
Explanation: The order of SN1 reaction is 1 because it has one Molecule (R-X) in its rate determining step. Explanation is given below:
Correct answer: 1- A. Retention of the configuration of the alkyl halide molecule
- B. Unimolecular reactions
- C. Reaction rate is a function of [alkyl halide]
- D. All of these
Explanation: SN1→ Unimolecular nucleophilic substitutionThey have 50% retention of Configuration and rate depends upon concentration of Alkyl halide.
Correct answer: All of these- A. Attack of the incoming nucleophile on alpha hydrogen
- B. Attack of the incoming nucleophile on beta hydrogen
- C. Attack of the incoming nucleophile on beta carbon
- D. Attack of incoming nucleophiles on electrophilic carbon
Explanation: β-elimination reactions are due to attack of the incoming nucleophile on beta hydrogen. β-Elimination involves attack of strong base (e.g.
Correct answer: Attack of the incoming nucleophile on beta hydrogen- A. SN1 and E1 reaction
- B. SN2 and E2 reaction
- C. SN2 and E1 reaction
- D. None of the above
Explanation: Tertiary alkyl halides have three R groups attached, and hence experience a high stearic hindrance.
Correct answer: SN1 and E1 reaction- A. Breakage of C-X and formation C-Nu bonds are simultaneous
- B. Inversion of the configuration of the alkyl halide molecule
- C. 2nd order kinetics
- D. All of these
Explanation: Option A, B, and C are all correct, all the 3 options represent the characterstic features of SN2 reactions.
Correct answer: All of these- A. Greater the bond energy of R-X, lesser the reactivity
- B. Greater the bond polarity of R-X, greater the reactivity
- C. Greater the bond energy of R-X, smaller the stability
- D. Greater E.N difference of R- X, lesser the stability
Explanation: Option C is correct. It gives an incorrect idea. Greater bond energy, makes the bond more stable.Note: Bond energy is always inversely…
Correct answer: Greater the bond energy of R-X, smaller the stability- A. Incoming nucleophile must be stronger than the leaving one
- B. Leaving nucleophile must be stronger than incoming nucleophile
- C. Tertiary alkyl halides generally give SN1 reactions
- D. SN2 is a single step mechanism
Explanation: SN reactions are favoured by a good leaving and stronger incoming group. Leaving nucleophile must be weaker than the incoming nucleophile.
Correct answer: Leaving nucleophile must be stronger than incoming nucleophile- A. Alcohol
- B. Alkane
- C. Alkyl halide
- D. Alkene
Explanation: β-Elimination reactions produce alkenes from alkyl halides.
Correct answer: Alkene- A. CH3-CI
- B. CH3-CH2-CH2-CI
- C. CH3-CH2-CI
- D. All have same reactivity
Explanation: SN2 mechanism is mostly shown by primary alkyl halides whereas tertiary alkyl halides show SN1 mechanism.
Correct answer: CH3-CI- A. OH-
- B. SH-
- C. NO2+
- D. I-
Explanation: As, Thioalcohol = R-SHHence reacting alkyl halide with SH- gives us a thioalcohol.
Correct answer: SH-- A. Steric hindrance
- B. Stability of carbocation
- C. Inductive effect
- D. All of these
Explanation: Greater steric hinderance, greater stability of R+ and greater inductive effect favours SN1.
Correct answer: All of these- A. SN1
- B. SN2
- C. Both A and B
- D. It does not show SN reaction
Explanation: Ter. butyl bromide is a tertiary alkyl halide, and tertiary alkyl halides favours SN1 reaction.
Correct answer: SN1- A. Homolytic cleavage
- B. Heterolytic cleavage
- C. Sometimes homolytic, sometimes heterolytic
- D. C-X bond is not cleaved in SN2 reactions
Explanation: In the SN2 (substitution nucleophilic bimolecular) mechanism of alkyl halides, the carbon-halogen (C-X) bond undergoes heterolytic…
Correct answer: Heterolytic cleavage- A. They are most reactive alkyl halide for a given alkyl group
- B. They show maximum boiling point for a given alkyl group
- C. Cannot be prepared directly by reaction of alkanes with I2
- D. All are true
Explanation: i) Due to low bond energy reactivity is highest. (ii) Greater polarizability of "I" increases boiling point.
Correct answer: All are true- A. Substitution
- B. Elimination
- C. Reduction
- D. Polymerization
Explanation: Alkyl halides, also known as haloalkanes, commonly undergo substitution reactions.
Correct answer: Substitution- A. 1₀- amine
- B. 2₀- amine
- C. 3₀- amine
- D. Mixture of I₀ ,2₀ and 3₀ amines
Explanation: When R - X is excess, these are enough R - X molecules to react with NH3 and make 1₀ ,2₀ and 3₀ amines.
Correct answer: Mixture of I₀ ,2₀ and 3₀ amines- A. C-X bond strength
- B. C-X bond polarity
- C. Both C- X bond strength and polarity
- D. Boiling point of the given R-X
Explanation: The main factor that decides the reactivity of alkyl halides is the bond strength of the C-X bond.
Correct answer: C-X bond strength- A. Substitution reactions
- B. Elimination reactions
- C. Favour both substitution and elimination reactions equally
- D. Cannot be predicted
Explanation: Higher polarizable nucleophile gives off electron easily to electrophilic carbon favouring substitution while it does not favour…
Correct answer: Substitution reactions- A. R3CX
- B. RCH2X
- C. R2CHX
- D. CH3X
Explanation: Smaller the R group greater the reactivity. Reactivity order towards SN2 CH3X >RCH2X>R2CHX increase in R-groups increase steric…
Correct answer: CH3X