Observe the given reaction schemes for the synthesis of an aromatic...

In Scheme 1, the reaction shown is the commercial preparation of phenol from cumene. Cumene (isopropylbenzene) is first oxidized in the presence of air ($O_2$) to form cumene hydroperoxide. This intermediate is then treated with dilute acid ($H_3O^+$) to undergo rearrangement and cleavage, yielding phenol and acetone as a byproduct. Since Y is specified as a ketone, Y is acetone (propan-2-one) and X is phenol.

In Scheme 2, aniline reacts with sodium nitrite ($NaNO_2$) and hydrochloric acid ($HCl$) at low temperatures ($273-278\text{ K}$) to undergo diazotization, forming benzene diazonium chloride. Thus, Z is benzene diazonium chloride. When benzene diazonium chloride is warmed with water, it hydrolyzes to form phenol, which confirms that X is phenol.

Therefore, the compounds are:
X = Phenol
Y = Propan-2-one
Z = Benzene diazonium chloride

Answer: X = Phenol, Y = Propan-2-one, Z = Benzene diazonium chloride