Which compound is formed when benzene is reacted with ethyl chloride in the presence of anhydrous aluminum chloride?

What is the total number of benzene derivatives with the molecular formula $C_6H_3Cl_3$?

Which of the following reactions is not possible for benzene due to its reversible nature?

Treatment of benzene with $CO / HCl$ in the presence of anhydrous $AlCl_3 / CuCl$ followed by reaction with $Ac_2O / NaOAc$ gives compound $X$ as the major product. Compound $X$ upon reaction with $Br_2 / Na_2CO_3$,followed by heating at $473 \ K$ with moist $KOH$ furnishes $Y$ as the major product. Reaction of $X$ with $H_2 / Pd-C$,followed by $H_3PO_4$ treatment gives $Z$ as the major product.
$(1)$ The compound $Y$ is
$(2)$ The compound $Z$ is
Identify the correct options for $(1)$ and $(2)$ respectively.

The cyclopentadienyl anion is:

In the mixture of conc. $H_2SO_4$ and $HNO_3$,the nitrating species is: