MCQs on Aromatic Hydrocarbons

Aromatic hydrocarbons are monocyclic or polycyclic. Most of the aromatic compounds contain a benzene ring. They are also known as arenes. In aromatic hydrocarbons, pi electrons are delocalised between carbon atoms in the cycle. Heterocyclic compounds following Huckel’s rule are also aromatic compounds. Benzene is the most popular aromatic hydrocarbon. They readily undergo electrophilic substitution reactions.

1. Find the true statement about benzene

(a) it possesses two types of C-C bonds

(b) three isomeric forms are possible in a monosubstituted benzene

(c) it readily undergoes addition due to unsaturation

(d) pi-electrons are delocalised in the ring

2. Nitration of benzene is carried out by which of the following reactive species?

(a) NO2+

(b) NO2

(c) HNO3

(d) NO3

3. In Chlorination of benzene, which of the following acts as an electrophile?

(a) Cl+

(b) Cl

(c) Cl

(d) FeCl3

4. Arenes do not show

(a) Delocalisation of pi-electrons

(b) Greater stability

(c) Resonance

(d) Electrophilic additions

5. Find the most stable carbonium ion among the following

(a) CH3CH2+

(b) C6H5CH2+

(c) C6H5CH2CH2+

(d) (C6H5)2CH+

6. Which of the following groups are most likely to be o, p directing?

(a) Deactivating

(b) Neutral

(c) Activating

(d) All of the above

7. The product formed predominantly in the reaction of toluene with chlorine in the presence of FeCl3 is

(a) m-chlorotoluene

(b) o- and p-chlorotoluene

(c) Benzoyl chloride

(d) Benzyl chloride

8. Which of the following will not undergo Friedel-Craft’s reaction readily?

(a) Toluene

(b) Xylene

(c) Cumene

(d) Nitrobenzene

9. The product formed, when benzene reacts with CH3COCl in the presence of AlCl3 is

(a) C6H5CH3

(b) C6H5Cl

(c) C6H5COCH3

(d) C6H5COCl

10. Find the reactants other than AlCl3 in Friedel-Craft’s alkylation

(a) C6H6 + CH4

(b) C6H6 + NH3

(c) C6H6 + CH3Cl

(d) C6H6 + CH3COCl

Answer

1. (d)

2. (a)

3. (a)

4. (d)

5. (d)

6. (c)

7. (b)

8. (d)

9. (c)

10. (c)

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