Engineering Chemistry Questions and Answers – Nucleophillic Substitution Reaction

This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Nucleophilic Substitution Reaction”.

1. The atom which defines the structure of a family of organic compounds and their properties is called ___________
a) Resonating structure
b) Homologous structure
c) Functional group
d) Nucleophile
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2. The functional group in alkyl halide is ___________
a) Hydroxyl group
b) Halogen atom
c) Inert gas
d) All of the mentioned
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3. The halide ion is an extremely ___________
a) Weak base
b) Weak acid
c) Strong base
d) Strong acid
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4. When the nucleophile :OR attacks the RX, the resultant product will be ___________
a) R – OH
b) ROR
c) R:CN
d) RNHR
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5. Select the correct statement from the following option.
a) S_N2 reaction follows second order kinetics
b) No intermediate is involved in S_N2 mechanism
c) S_N2 reactions are one-step reaction
d) All of the mentioned
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6. The reactivity order of alkyl halides in S_N2 is ___________
a) CH₃ X > 1⁰ > 2⁰ > 3⁰
b) CH₃ X > 2⁰ > 1⁰ > 3⁰
c) CH₃ X > 3⁰ > 1⁰ > 2⁰
d) CH₃ X > 3⁰ > 2⁰ > 1⁰
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7. S_N1 reaction involves heterolysis to form the carbocation as an intermediate.
a) True
b) False
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8. Which step in S_N1 reaction is a slow rate determining step?
a) Attack of nucleophile
b) Formation of a racemic mixture
c) Formation of a transition state
d) All of the mentioned
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9. A low concentration of nucleophile favours the ___________
a) S_N2 reaction
b) S_N1 reaction
c) Both S_N1 and S_N1 reaction
d) None of the mentioned
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10. Which of the following reactions are favoured by polar aprotic solvent?
a) S_N1 reactions
b) S_N2 reactions
c) Both S_N1 and S_N1 reactions
d) None of the mentioned
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11. Arrange the following in the decreasing order of leaving group in nucleophilic substitution reaction.
a) H^– > Cl^– > HO^– > Br^– > CH₃COO^–
b) Cl^– > Br^– > HO^– > H^– > CH₃COO^–
c) Cl^– > Br^– > CH₃COO ^– > HO^– > H^–
d) HO^– > CH₃COO ^– > H^– > Br^– > Cl^–
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12. Reaction of alcohol with SOCl₂ is ___________
a) S_N1
b) S_N2
c) S_NAr
d) S_Ni
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13. The nucleophilic substitutions do not occur in haloarenes because ___________
a) The carbon-halogen bond is much shorter
b) The carbon-halogen bond is stronger compared to that in haloalkanes
c) The lone pair of electrons on the halogen participates in delocalisation with the π-electrons of benzene ring
d) All of the mentioned
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14. Which of the following drastic condition is required for the substitution in haloarenes?
a) High temperature
b) High pressure
c) Strong concentrated reagent
d) All of the mentioned
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15. The rate of nucleophilic substitution reactions are higher in the presence of ___________
a) Electron withdrawing groups
b) Electron releasing groups
c) Both electron withdrawing and releasing groups
d) None of the mentioned
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Sanfoundry Global Education & Learning Series – Engineering Chemistry.

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