Hydrocarbons (Aliphatic & Aromatic) Quiz - ICSE Class 11 Chemistry
Free practice quiz: Hydrocarbons (Aliphatic & Aromatic) (ICSE Class 11 Chemistry). 47 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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Which of the following is the correct IUPAC name for tert-butylbenzene?
- 1,1-dimethylethylbenzene
- phenyl-tert-butane
- (1-methylethyl)benzene
- tert-butylbenzene
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Answer: A. 1,1-dimethylethylbenzene
The IUPAC naming convention for alkylbenzenes prioritizes the benzene ring as the parent. The tert-butyl group is a C(CH3)3 group attached to the benzene ring. The tert-butyl group is named as 1,1-dimethylethyl. Therefore, tert-butylbenzene is correctly named as 1,1-dimethylethylbenzene.
The compound formed by the reaction of benzene with acetyl chloride in the presence of anhydrous aluminium chloride is:
- Ethylbenzene
- Acetophenone
- Benzaldehyde
- Benzyl alcohol
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Answer: B. Acetophenone
This is a Friedel-Crafts acylation reaction. Benzene reacts with acetyl chloride (CH3COCl) in the presence of AlCl3. The acylium ion (CH3CO+) is the electrophile, which attacks the benzene ring. This leads to the formation of acetophenone, also known as phenyl methyl ketone.
Which of the following reactions is an example of electrophilic addition?
- Addition of HBr to propene
- Addition of Br2 to benzene
- Dehydrohalogenation of bromoethane
- Wurtz reaction
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Answer: A. Addition of HBr to propene
Electrophilic addition is characteristic of alkenes and alkynes. The pi electrons of the double bond act as a nucleophile, attacking an electrophile, which then adds to the molecule. The addition of HBr to propene involves the attack of the pi bond on H+, making it an electrophilic addition. Addition of Br2 to benzene is electrophilic aromatic substitution, dehydrohalogenation is elimination, and Wurtz reaction is coupling.
What product is formed when benzene is heated with excess of cold concentrated sulfuric acid?
- Benzenesulfonic acid
- 1,2-benzenedisulfonic acid
- 1,3-benzenedisulfonic acid
- 1,4-benzenedisulfonic acid
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Answer: A. Benzenesulfonic acid
Benzene undergoes sulfonation with concentrated sulfuric acid. At lower temperatures and with a limited amount of sulfuric acid, monosulfonation occurs, yielding benzenesulfonic acid. Disulfonation requires higher temperatures and/or fuming sulfuric acid.
Which reaction is characteristic of aromatic compounds, preserving the aromaticity of the ring?
- Addition of H2
- Addition of Br2 under UV light
- Electrophilic substitution
- Combustion
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Answer: C. Electrophilic substitution
Aromatic compounds are stabilized by delocalized pi electrons, and they readily undergo electrophilic substitution reactions where an electrophile replaces a hydrogen atom on the ring, thereby maintaining the aromatic system. Addition reactions typically disrupt aromaticity.