Benzene + $CH_3-CH_2-CH_2-Cl$ $\xrightarrow{AlCl_3}$ the product is:

Which of the following is an example of an electrophilic substitution reaction?

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:
$CH_3CH_2CH_2CH_2Br$ $\xrightarrow[\text{dry ether}]{Na} X$ $\xrightarrow[\text{10-20 atm}]{\text{Cr}_2\text{O}_3 / 773 \text{ K}} Y$ $\xrightarrow[\text{anhy. AlCl}_3]{\text{CH}_3\text{COCl}} Z$

Benzene on treatment with a mixture of conc. $HNO_3$ and conc. $H_2SO_4$ at $100 \ ^oC$ gives

What is meant by a meta-directing group? Give examples of it and explain the meta-directing effect of $-NO_2$.

Point out the wrong statement in relation to the structure of benzene.