WorksheetsPOC-II_Unit-I_quizz
Total questions: 15
Worksheet time: 13mins
Which of the following is a correct statement regarding the physical properties of benzene?
It is a dense liquid, heavier than water
It is a solid at room temperature (25 °C)
It has a melting point just above the freezing point of water
It is highly soluble in water
In 1865, August Kekulé proposed a structure for benzene. What was the key feature of this structure?
A straight-chain hydrocarbon with six carbons
A cyclic, planar ring of six carbons with alternating single and double bonds
A three-dimensional cage-like structure of carbon and hydrogen
A ring where all carbon-carbon bonds are identical
Benzene primarily undergoes substitution reactions because:
Its ring structure has high angle strain
It has localized electrons that are easily attacked
Addition reactions would destroy its stable aromatic ring
It lacks a continuous chain of carbon atoms
The fundamental reason benzene prefers substitution over addition is due to its:
Aromaticity and delocalized pi-electron cloud
Lack of hydrogen atoms
Ability to form free radicals easily
Linear and unbranched structure
What is the hybridization of the carbon atoms in benzene?
sp2
sp
sp3d
sp3
What type of reaction does benzene typically undergo when reacting with bromine in the presence of a catalyst?
Nucleophilic substitution
Electrophilic substitution
Free radical substitution
Electrophilic addition
Why is the experimentally measured heat of hydrogenation of benzene significantly lower than the theoretical value calculated for three isolated double bonds?
Because benzene has alternating single and double bonds
Due to the extra stability provided by resonance in the benzene ring
Because the hydrogenation reaction is incomplete
Due to the presence of impurities in the sample
If the heat of hydrogenation for one typical double bond is ~28.6 kcal/mol, what would be the expected (theoretical) heat of hydrogenation for a molecule with three isolated double bonds, like hypothetical non-aromatic cyclohexatriene?
28.6 kcal/mol
49.8 kcal/mol
85.8 kcal/mol
150.0 kcal/mol
According to the Kekulé model of benzene, what would the structure suggest about the carbon-carbon bonds?
All bonds are identical in length
The bonds alternate between longer and shorter lengths
All bonds are of an intermediate length
The bond lengths are unpredictable
The type of reaction where an electrophile replaces a hydrogen atom on a benzene ring is called (a) substitution.
A substituent like -NO₂ is an electron- (a) group, which makes the benzene ring less reactive towards electrophilic aromatic substitution.
The -OH group is an example of an electron- (a) group, which increases the benzene ring's reactivity.
Because an -NH₂ group donates electron density to the ring, it is classified as an (a) group, making the benzene ring more reactive toward electrophiles.
In the nitration mechanism, the electrophile that attacks the benzene ring is the (a) ion.
The electrophilic substitution reaction where a hydrogen atom on benzene is replaced by a -SO₃H group is called ________.
Sulfonation
Sulfation
Sulfurization
Sulfhydration
