Class 12 Chemistry Chapter 10 Haloalkanes and Haloarenes MCQs | Class 12 Chemistry Chapter 10 Haloalkanes and Haloarenes Multiple Choice Questions (MCQs) and Answers

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Questions
1 C-Cl bond of chlorobenzene in comparison to C-Cl bond in methyl chloride is
A Longer and weaker
B Shorter and weaker
C Shorter and stronger
D Longer and stronger

Answer:Shorter and stronger
2 A solution of (+) 2-chloro-2-phenylethane in toluene racemises slowly in the presence of a small amount of SbCl5, due to the formation of
A carbanion
B carbene
C free radical
D carbocation

Answer:carbocation
3 Phosgene is commonly known as
A thionyl chloride
B carbonyl chloride
C carbon dioxide and phosphine
D phosphoryl chloride

Answer: carbonyl chloride
4 The reaction of tert butyl bromide with sodium methoxide produces mainly
A isobutane
B isobutylene
C tert-butyl methyl ether
D sodium tert butoxide

Answer: isobutylene
5 Which of the following undergoes nucleophilic substitution exclusively by SN1 mechanism?
A Benzyl Chloride
B Ethyl chloride
C Chlorobenzene
D Isopropyl chloride

Answer: Benzyl Chloride
6 The increasing order of nucleophilicity would be?
A Cl– < Br– < I–
B I– < Cl– < Br–
C Br– < Cl– < F–
D I– < Br– < Cl–

Answer:Cl– < Br– < I–
7 Which of the following is most reactive towards SN1 reaction?
A C6H5C(CH3)C6H5Br
B C8H5CH2Br
C C6H5CH(C6H5)Br
D C6H5CH(CH3)Br

Answer:C6H5C(CH3)C6H5Br
8 CH3CH2CH2Br + NaCN → CH3CH2CH2CN + NaBr, will be fastest in
A ethanol
B methanol
C N, N-dimethylformamide
D Water

Answer:N, N-dimethylformamide
9 A Grignard reagent may be made by reacting magnesium with
A Methyl amine
B Diethyl ether
C Ethyl iodide
D Ethyl alcohol

Answer:Ethyl iodide
10 Which of the following undergoes nucleophilic substitution exclusively by SN 1 mechanism?
A Benzyl chloride
B Ethyl chloride
C Chlorobenzene
D Isopropyl chloride

Answer:Benzyl chloride
11 The increasing order of nucleophilicity would be
A Cl– < Br– < I–
B I– < Cl– < Br–
C Br– < Cl– < F–
D I– < Br– < Cl–

Answer:Cl– < Br– < I–
12 Which of the following is most reactive towards SN1 reaction?
A C6H5C(CH3)C6H5Br
B C6H5CH2Br
C C6H5CH(C6H5)Br
D C6H5CH(CH3)Br

Answer:C6H5C(CH3)C6H5Br
13 CH3CH2CH2Br + NaCN → CH3CH2CH2CN + NaBr, will be fastest in
A ethanol
B methanol
C N, N dimethyl formamide
D Water

Answer: N, N dimethyl formamide
14 A dihalogen derivative ‘X’ of a hydrocarbon with three carbon atoms react with ale. KOH and produces hydrocarbon which forms red ppt. with ammonical Cu2Cl2. ‘X’ gives an aldehyde on reaction with aq. KOH. The compound ‘X’ is
A 1, 3-Dichloropropane
B 1, 2-Dichloropropane
C 2, 2-Dichloropropane
D 1, 1-Dichloropropane

Answer: 1, 1-Dichloropropane
15 The synthesis of alkyl fluoride is best accomplished by
A Finkelstein reaction
B Swartz reaction
C Free radical fluorination
D Sandmeyers reaction

Answer:Swartz reaction
16 How many chiral compounds are possible on monochlorination of 2-methyl butane?
A 2
B 4
C 6
D 8

Answer: 2
17 Which of the following alkyl halides will undergo SN1 reaction most readily?
A (CH3)3 C—F
B (CH3)3 C—Cl
C (CH3)3 C—Br
D (CH3)3 C—I

Answer: (CH3)3 C—I
18 Which of the following compounds will give racemic mixture on nucleophilic substitution by OH” ion?
1-Bromoethane, 1-Bromopropane, 1-Bromobutane, Bromobenzene
A Bromobenzene < 1-Bromobutane < 1-Bromopropane < 1-Bromoethane
B Bromobenzene < 1-Bromoethane < 1-Bromopropane < 1-Bromobutane
C 1-Bromopropane < 1-Bromobutane < 1-Bromoethane < Bromobenzene
D 1-Bromoethane < 1-Bromopropane < 1-Bromobutane < Bromobenzene

Answer:Pentane – 1, 2, 3, 4 – tetraol
19 SN1 reaction of alkyl halides lead to
A Retention of configuration
B Racemisation
C Inversion of configuration
D None of these

Answer: Racemisation
20 p-djchlorobenzene has higher melting point than its o- and m- isomers because
A p-dichlorobenzene is more polar than o- and m- isomer
B p-isomer has a symmetrical crystalline structure
C boiling point of p-isomer is more than o- and m-isomer
D All of these are correct reasons

Answer: p-isomer has a symmetrical crystalline structure

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