Question 61: Nomenclature – Isomer Identification
Which of the following haloalkanes is an isomer of 2-chlorobutane?
A) 1-chloropropane
B) 1-chloro-2-methylpropane
C) 2-chloro-2-methylpropane
D) 1,2-dichlorobutane
Answer: B) 1-chloro-2-methylpropane
Explanation:
1-Chloro-2-methylpropane has the same molecular formula as 2-chlorobutane but a different structure, making them isomers.
Question 62: Reactions – Synthesis of Haloarenes
Which reagent is used to synthesize bromobenzene from benzene?
A) Br₂ with FeBr₃
B) HBr with peroxides
C) NaBr with H₂SO₄
D) Br₂ with AlCl₃
Answer: A) Br₂ with FeBr₃
Explanation:
Bromobenzene is synthesized by the bromination of benzene using Br₂ in the presence of a FeBr₃ catalyst.
Question 63: Physical Properties – Methyl Halides
Which methyl halide has the highest boiling point?
A) CH₃F
B) CH₃Cl
C) CH₃Br
D) CH₃I
Answer: D) CH₃I
Explanation:
Boiling points increase with increasing molecular weight and polarizability. CH₃I has the highest boiling point among methyl halides due to its larger atomic size.
Question 64: Nomenclature – Multiple Functional Groups
What is the IUPAC name for CH₃-CHCl-CHBr-CH₃?
A) 2-Chloro-3-bromobutane
B) 3-Chloro-2-bromobutane
C) 2-Bromo-3-chlorobutane
D) Both A and C
Answer: D) Both A and C
Explanation:
Both 2-Chloro-3-bromobutane and 2-Bromo-3-chlorobutane are correct as the numbering can start from either end, providing the same set of locants.
Question 65: Reactions – Reactivity of Haloalkanes
Which haloalkane is most likely to undergo E2 elimination?
A) CH₃CH₂Cl
B) (CH₃)₂CHCl
C) (CH₃)₃CCl
D) CH₃Cl
Answer: C) (CH₃)₃CCl
Explanation:
(CH₃)₃CCl is a tertiary haloalkane, which readily undergoes E2 elimination due to the formation of a stable tertiary alkene.
Question 66: Properties – Physical State
Which haloalkane is a gas at room temperature?
A) CH₃Cl
B) C₂H₅Cl
C) C₃H₇Cl
D) (CH₃)₃CCl
Answer: A) CH₃Cl
Explanation:
CH₃Cl (methyl chloride) is a gas at room temperature due to its small molecular size and low boiling point.
Question 67: Nomenclature – Binary Naming
What is the common name for 1-bromoethane?
A) Ethyl bromide
B) Ethylene bromide
C) Bromoethane
D) Both A and C
Answer: D) Both A and C
Explanation:
1-Bromoethane is commonly known as Ethyl bromide or simply Bromoethane.
Question 68: Reactions – Synthesis Pathway
Which sequence of reactions can convert 1-propanol to 1-propyl bromide?
A) Dehydration followed by bromination
B) Oxidation followed by substitution
C) Sulfonation followed by elimination
D) Conversion to tosylate followed by substitution
Answer: D) Conversion to tosylate followed by substitution
Explanation:
1-Propanol can be converted to 1-propyl tosylate and then undergo nucleophilic substitution with NaBr to form 1-propyl bromide.
Question 69: Properties – Molecular Dipole
Which haloalkane has the smallest dipole moment?
A) CH₃Cl
B) CH₃CH₂Cl
C) (CH₃)₂CHCl
D) (CH₃)₃CCl
Answer: D) (CH₃)₃CCl
Explanation:
(CH₃)₃CCl has the smallest dipole moment due to its symmetrical, highly branched structure, which reduces overall molecular polarity.
Question 70: Reactions – Haloalkane Hydrolysis
What type of reaction is involved in converting 2-chloropropane to 2-propanol?
A) Elimination
B) Nucleophilic substitution
C) Electrophilic addition
D) Radical substitution
Answer: B) Nucleophilic substitution
Explanation:
Conversion of 2-chloropropane to 2-propanol involves an SN2 or SN1 nucleophilic substitution where the chlorine is replaced by a hydroxyl group.
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