Number of $\pi$-bonds present in $B.H.C.$ ($Benzene$ $hexachloride$) are

The rate of nitration will be

Deduce the structure of $(A)$.
$(A) \ C_{8}H_{10}$ $\xrightarrow{KMnO_{4}} (B) \ C_{8}H_{6}O_{4}$ $\xrightarrow[Fe]{Br_{2}} C_{8}H_{5}BrO_{4} (C)$ (one-product only)

The number of possible isomers of dichloro-nitrobenzene is

Given below are two statements:
Statement $I$: Nitration of benzene involves the following step:
$H-O^+(H)-NO_2 \rightleftharpoons H_2O + NO_2^+$
Statement $II$: Use of Lewis base promotes the electrophilic substitution of benzene.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which of the following represents $H$ückel's rule for aromaticity?