Which of the following compounds is planar in shape?

What is aromaticity? Explain with suitable examples. State the Huckel rule and explain it with a suitable example. Write the requirements for aromatic character in a compound. Show aromatic structures having $1$,$2$,and $3$ rings with suitable examples.

The six carbon atoms of benzene are of:

Benzene is treated with oleum to produce compound $(X)$,which when further heated with molten sodium hydroxide followed by acidification produces compound $(Y)$. The compound $(Y)$ is treated with zinc metal to produce compound $(Z)$. Identify the structure of compound $(Z)$ from the following options.

Which of the following reactions is correct?

Which of the following species is used as a reagent in the Friedel-Crafts alkylation reaction?