Engineering Chemistry MCQ (Electrophillic Substitution Reaction – 2)

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Engineering Chemistry MCQ (Electrophillic Substitution Reaction – 2)

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1. An activating substituent group activates ___________
a) Ortho position
b) Para position
c) Both ortho and para positions
d) Meta position
Answer: b
Explanation: An activating substituent group activates the ortho and para positions. It does not activate the meta position.

2. A deactivating substituent group directs ___________
a) Ortho position
b) Para position
c) Both ortho and para positions
d) Meta position
Answer: d
Explanation: A deactivating substituent group directs only meta position. It does not activate ortho or para positions.

3. Which of the following is ortho-para directing group?
a) –NHCOCH3
b) –NO2
c) –CN
d) –CHO
Answer: a
Explanation: NHCOCH3 is ortho-para directing group. NO, CN and CHO are metadirecting groups.

4. Which of the following is a meta directing group?
a) –NHCOCH3
b) –COOH
c) –OH
d) –OCH3
Answer: b
Explanation: -COOH is a meta directing group. All the other options are ortho-para directing groups.

5. The most stable carbonium ion is ___________
a) Methyl carbonium ion
b) 20 carbonium ion
c) 10 carbonium ion
d) 30 carbonium ion
Answer: d
Explanation: The most stable crbonium ion is 30 carbonium ion. The least stable is primary or 10 carbonium ion.

6. Which of the following has the highest activation of the benzene ring?
a) – NHCOCH3
b) –OH
c) –NH2
d) –C6H5
Answer: c
Explanation: –NH2 among the following has the highest activation of the benzene
ring. In cases where the substituents are esters or amides, they are less activating
because they form resonance structure that pull the electron density away from the ring.

7. HBr reacts fastest with ___________
a) 2-methylpropan-2-ol
b) Propan-1-ol
c) Propan-2-ol
d) 2-methylpropan-1-ol
Answer: a
Explanation: HBr reacts fastest with 2-methylpropan-2-ol. Hydrogen bromide is the
diatomic molecule and a colorless compound.

8. The compound that can be most readily sulphonated is ___________
a) Benzene
b) Nitrobenzene
c) Toluene
d) Chlorobenzene
Answer: c
Explanation: The compound that can be most readily sulphonated is toluene. Toulene contains CH3 group.

9. In Cannizaro reaction, two molecules of aldehydes are reacted to produce ___________
a) Alcohol only
b) Carboxylic acid only
c) Alcohol and carboxylic acid
d) Alcohol, carboxylic acid and ketone
Answer: c
Explanation: In Cannizaro reaction, two molecules of aldehydes are reacted to produce alcohol and carboxylic acid using a hydroxide base.