How many $\pi$ electrons are there in the following species:

Write the sulphonation reactions of benzene.

Product $(B)$ is

Which of the following is a Friedel-Crafts reaction $(FCR)$?

Which of the following statements are correct with respect to benzene?
$(i)$ It forms triozonide with $O_3$.
$(ii)$ It is non-planar.
$(iii)$ It forms only one monosubstituted product with $CH_3COCl$ in the presence of anhydrous $AlCl_3$.
$(iv)$ It forms hexachlorobenzene on heating with $Cl_2$ under photochemical conditions.

Which of the following Friedel-Crafts reactions is incorrectly written?