Five isomeric para - disubstituted aromatic compounds $\mathrm{A}$ to $\mathrm{E}$ with molecular formula ${\mathrm{C}}_8{\mathrm{H}}_8{\mathrm{O}}_2$ were given for identification. Based on the following observations, give the structures of the compounds:
(i) Both $\mathrm{A}$ and $\mathrm{B}$ form a silver mirror with Tollen's reagent; also, $\mathrm{B}$ gives a positive test with ${\mathrm{FeCl}}_3$ solution.
(ii) $\mathrm{C}$ gives a positive infoform test.
(iii) $\mathrm{D}$ is readily extracted in aqueous ${\mathrm{NaHCO}}_3$ solution.
(iv) $\mathrm{E}$ on acid hydrolysis gives $1,4-$ dihydroxy benzene.
Find compound $\mathrm{E}$?