What are the major products $X$ and $Y$ respectively in the following set of reactions?

Write about the physical properties of benzene.

In the Friedel-Crafts reaction,toluene can be prepared by using:

Explain the halogenation of benzene with the example of chlorination.

Which of the following aromatic compounds undergoes sulphonation reaction most easily?

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