For a compound with molecular formula $C_7 H_8 O$,how many aromatic structures are possible?

The number of $\sigma$ and $\pi$ bonds in a molecule of benzene is

In the following sequence of reactions,the maximum number of atoms present in molecule $C$ in one plane is:
$A$ $\xrightarrow[Cu \text{ tube}]{\text{Red hot}} B$ $\xrightarrow[\text{Anhydrous } AlCl_3]{CH_3Cl (1 \text{ eq})} C$
($A$ is the lowest molecular weight alkyne)

Identify the molecular formula of pyridine from the following.

Explain why the following systems are not aromatic?

Which of the following compounds possesses the $C-H$ bond with the lowest bond dissociation energy?