The compound '$A$' with molecular formula $C_8H_{10}$ (aromatic) which gives $1$ mononitro substituted product and $3$ dinitro substituted products is:

Consider the reaction sequence below:
Anisole $\xrightarrow[AlCl_3]{\text{Succinic anhydride}} A$ $\xrightarrow[\text{Clemmensen's reduction}]{\text{Cyclization}} X$
Identify $X$.

Choose the best method to prepare the given compound:

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 total number of aromatic species generated in the following reactions is:

Consider the following sequence of reactions. In $Z$,the number of $sp^3$ carbons is $a$ and $sp^2$ carbons is $b$. The value of $(a+b)$ is:
$CH_3CH_2CH_2CH_2Br$ $\xrightarrow[\text{dry ether}]{Na} X$ $\xrightarrow[\text{10-20 atm}]{\text{Cr}_2\text{O}_3 / 773 \text{ K}} Y$ $\xrightarrow[\text{anhy. AlCl}_3]{\text{CH}_3\text{COCl}} Z$