Treatment of benzene with CO/HCl in the presence of anhydrous  $AlC{l}_3/CuCl$ followed be reaction with  $A{c}_{2}O/NaOAc$ gives compound X as the major product. Compound X upon reaction with  $B{r}_2/N{a}_{2}C{O}_3$, followed by heating at 473 K with alc. KOH furnishes Y as the major product. Reaction of X with  $H_2/Pd-C$, followed by  $H_{3}P{O}_4$ treatment gives Z as the major product.

(Hint: compound Y form white precipitate with Tollens reagent)