Organic Chemistry Multiple Choice Questions on “Aromatic Hydrocarbons”.
1. Identify the correct statement which is related to aromatic hydrocarbon?
a) It has only sigma bonds
b) It has only pi bonds
c) It has a sigma and two pi bonds
d) It has a sigma and delocalized pi bond
Answer: d
Clarification: An aromatic hydrocarbon always has a sigma as well as a delocalized pi bond found between the carbon atoms.
2. Select the incorrect option.
a) The aromatic hydrocarbon has a pleasant aroma (smell)
b) Some of the aromatic compounds are ring-shaped
c) Aromatic hydrocarbon can be either mono or polycyclic
d) Benzene is the simplest hydrocarbon
Answer: b
Clarification: All the aromatic hydrocarbon are ring shaped as all of them are sp2 hybridized with a geometry of trigonal planar.
3. Which among the following is not a property of aromatic hydrocarbon?
a) These compounds have very good aromaticity
b) These compounds have excellent stability
c) These compounds do not undergo nucleophilic substitutions but they undergo electrophilic substitutions
d) There exists a strong ratio between carbon and hydrogen
Answer: c
Clarification: Aromatic hydrocarbons undergo both electrophilic and nucleophilic aromatic substitutions.
4. Arenes does not undergo ___________
a) Dehydrogenation
b) Coupling reaction
c) Halogenation
d) Cyclo additions
Answer: a
Clarification: Arenes undergo hydrogenation reaction and form saturated ring products.
5. Which among these is not a representative arene compound?
a) Durene
b) Picric chloride
c) Aspirin
d) Mesitylene
Answer: b
Clarification: Picric acid is a representative arene compound but not picric chloride.
6. Which among these is the simplest example for polycyclic arenes?
a) Benzacephenanthrylene
b) Naphthalene
c) Pyrene
d) Dibenz-anthracene
Answer: b
Clarification: Naphthalene has fused ring of aromaticity and has the simplest structure when compared with other polycyclic aromatic hydrocarbons.
7. Arenes are polar.
a) True
b) False
Answer: b
Clarification: Arenes are insoluble in water and hence they are non polar compounds.
8. Arenes are _________
a) volatile
b) Water soluble
c) Non-carcinogenic
d) Mostly gases
Answer: a
Clarification: Arenes have a very low boiling point and hence they are volatile in nature.
9. The main sources of these arenes are _________
a) Petroleum
b) Biogas and petroleum
c) Petroleum and coal tar
d) Natural gas
Answer: c
Clarification: As these petroleum and natural gas comprise of naturally occurring compounds such as carbon and hydrogen in abundance, these serve as the main source of arenes.
10. Benzene has a stronger Vander-Waal’s force than Methylbenzene.
a) False
b) True
Answer: a
Clarification: The benzene molecule is smaller than that of the methylbenzene and hence it does not have the Vander-Waal’s forces as equal to those of methylbenzene.