$\mathrm{C}-\mathrm{O}$ bond with benzene ring cannot undergo cleavage due to resonance, it develop partial double bond character.


(ii) ${\mathrm{C}}_6{\mathrm{H}}_5-\mathrm{O}-{\mathrm{C}}_6{\mathrm{H}}_5\to \mathrm{X}$
Due to the positive charge on benzene ring $\left(\mathrm{C}\mathrm{s}{\mathrm{P}}^2\right)$ is a highly unstable.
(iii)

(iv)