Which of the following compounds is not aromatic?

The reaction of benzene with a mixture of concentrated $HNO_3$ and concentrated $H_2SO_4$,followed by treatment with $Cl_2 / FeCl_3$,gives:

The ease of nitration of the following three hydrocarbons follows the order: $(I)$ Toluene, $(II)$ $m$-Xylene, $(III)$ $p$-Xylene.

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

The reaction sequence is as follows:
$1,4-dibromocyclohex-2-ene$ $\xrightarrow[{2 \, molar \, equivalent}]{{(CH_3)_2NH}} (A)$ $\xrightarrow{{BaO}} (B)$ $\xrightarrow[{ (2 \, molar \, equivalent) }]{{CH_3I}} (C)$ $\xrightarrow{{Ag_2O \, / \, H_2O}} (D) + 2(CH_3)_3N$
Identify the end product $(D)$ in the given sequence.

The correct order of reactivity in electrophilic substitution reaction of the following compounds is: