An isomer of $\mathrm{C}{}_7\mathrm{H}{}_8\mathrm{O}$ gives violet colour with neutral $\mathrm{FeCl}{}_3$, and with excess bromine water it gives a white precipitate in which three hydrogen atoms of the ring have been replaced by bromine. The compound is

The violet colour shows a phenolic $-\mathrm{OH}$, which excludes methoxybenzene. Bromine enters the free positions ortho and para to $-\mathrm{OH}$. 2-Methylphenol has only positions 4 and 6 free, 4-methylphenol only 2 and 6, but in 3-methylphenol positions 2, 4 and 6 are all free, giving the tribromo product.