Question

________ is a planar regular hexagon, with bond angles of ${120^{\text{o}}}$.
A.Nitrobenzene
B.Benzene
C.Methyl benzene
D.None of these

Answer 1

Benzene and its derivatives are aromatic compounds and have a significant involvement in organic chemistry. To answer this question, we must recall the arrangement of atoms in benzene and in the functional groups in their derivatives.

Complete answer:
We know that benzene is a six- membered carbon ring. Each carbon atom is $s{p^2}$ hybridized and bonded to two other carbon atoms and one hydrogen atom. Since the hybridization is $s{p^2}$, all the bonds formed by carbon are arranged in trigonal planar form and the bond angles are equal to ${120^{\text{o}}}$. All the atoms lie in a single plane and the whole ring is planar.
Meanwhile in nitro benzene, the nitro group and the methyl group in methyl benzene are non-planar groups.

Thus, the correct answer is B.
Note:
The criteria for a compound to be aromatic given by the Huckel’s rule of aromaticity are:
The molecule under consideration must be cyclic, i.e., it must have a ring structure.
The molecule under consideration must have all carbons $s{p^2}$ hybridized and the system must be a fully conjugated one.
All the atoms of the molecule must lie in the same plane, i.e., the molecule must be planar.
The number of $\pi$electrons in the system must be equal to $4n + 2$ where $n$ is a whole number.
Benzene has 3 double bonds and thus a total of 6 $\pi$ electrons which is equal to $4n + 2$ where $n$ is a whole number. It also follows all the other requirements and is thus aromatic.