Nitrobenzene can be prepared from benzene by using a mixture of conc. $HNO_3$ and conc. $H_2SO_4$. In the nitrating mixture,$HNO_3$ acts as a

The number of benzene derivatives of the formula $C_7H_8O$ is :

Which of the following groups,when attached to a benzene ring,acts as a deactivating meta-directing group?

Assertion : Benzene exhibits two different bond lengths, due to $C-C$ single and $C=C$ double bonds.
Reason : Actual structure of benzene is a hybrid of the following two structures.

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 decreasing order of the rate of electrophilic aromatic substitution is: