Question 71: Nomenclature – Naming Haloalkenes
What is the IUPAC name for CH₂=CH-CH₂-Cl?
A) 1-Chloropropene
B) 2-Chloropropene
C) Chloroethene
D) Vinyl chloride
Answer: B) 2-Chloropropene
Explanation:
The chlorine is attached to the second carbon in the propene chain, so the name is 2-Chloropropene.
Question 72: Reactions – Synthesis of Haloarenes
Which reagent is used to convert toluene to p-chlorotoluene?
A) Cl₂ with FeCl₃
B) HCl with AlCl₃
C) NaCl with UV light
D) SOCl₂
Answer: A) Cl₂ with FeCl₃
Explanation:
Chlorination of toluene with Cl₂ in the presence of FeCl₃ selectively forms p-Chlorotoluene due to the directing effects of the methyl group.
Question 73: Physical Properties – Comparison with Alkanes
Compared to alkanes, haloalkanes generally have:
A) Higher boiling points
B) Lower boiling points
C) Similar boiling points
D) No systematic difference
Answer: A) Higher boiling points
Explanation:
Haloalkanes have higher boiling points than alkanes of similar molecular weight due to dipole-dipole interactions and increased molecular polarity.
Question 74: Nomenclature – Cyclohexane Derivatives
What is the IUPAC name for 1,4-dichlorocyclohexane?
A) cis-1,4-Dichlorocyclohexane
B) trans-1,4-Dichlorocyclohexane
C) 1,4-Dichlorocyclohexane
D) Both A and B depending on stereochemistry
Answer: D) Both A and B depending on stereochemistry
Explanation:
1,4-Dichlorocyclohexane can exist as cis or trans isomers, so the IUPAC name includes the stereochemistry: cis-1,4-Dichlorocyclohexane or trans-1,4-Dichlorocyclohexane.
Question 75: Reactions – Effect of Substituents
How does the presence of a nitro group on a haloarene affect its reactivity towards nucleophilic substitution?
A) Increases reactivity
B) Decreases reactivity
C) No effect
D) Depends on the position
Answer: A) Increases reactivity
Explanation:
A nitro group is a strong electron-withdrawing group that activates the aromatic ring towards nucleophilic substitution by stabilizing the intermediate.
Question 76: Properties – Haloalkane Types
Which type of haloalkane is CH₃CHBrCH₃?
A) Primary
B) Secondary
C) Tertiary
D) Methyl
Answer: B) Secondary
Explanation:
The carbon bonded to the bromine is attached to two other carbon atoms, making it a secondary haloalkane.
Question 77: Nomenclature – Di- and Tri-substituted Haloalkanes
What is the IUPAC name for CH₃-CCl₂-CH₂-CH₃?
A) 2,2-Dichlorobutane
B) 1,2-Dichlorobutane
C) 3,3-Dichlorobutane
D) 1,1-Dichlorobutane
Answer: A) 2,2-Dichlorobutane
Explanation:
Both chlorine atoms are on the second carbon of a four-carbon chain, so the name is 2,2-Dichlorobutane.
Question 78: Reactions – Substituent Effects
Which substituent on a benzene ring deactivates it towards electrophilic substitution?
A) -OH
B) -NH₂
C) -NO₂
D) -CH₃
Answer: C) -NO₂
Explanation:
The -NO₂ group is a strong electron-withdrawing group that deactivates the benzene ring towards electrophilic substitution.
Question 79: Physical Properties – Hydrogen Halides
Which hydrogen halide has the highest boiling point?
A) HCl
B) HBr
C) HI
D) HF
Answer: D) HF
Explanation:
HF has the highest boiling point among hydrogen halides due to strong hydrogen bonding between molecules.
Question 80: Nomenclature – Chiral Haloalkanes
What is the IUPAC name for CH₃-CH(Cl)-CH₂-Br?
A) 2-Chloro-3-bromopropane
B) 2-Bromo-3-chloropropane
C) 2-Chloro-1-bromopropane
D) 1-Chloro-2-bromopropane
Answer: D) 1-Chloro-2-bromopropane
Explanation:
Number the chain to give substituents the lowest numbers. Chlorine is on carbon 1 and bromine on carbon 2, making the name 1-Chloro-2-bromopropane.
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