A compound ' X ' is acidic and it is soluble in NaOH solution, but insoluble in NaHCO 3 solution.…

Generally alcohols are acidic in nature but they does not react with NaOH solution. Among the given options only phenol is acidic enough to react with NaOH solution. 

So, compound '$\mathrm{X}$' is phenol which is acidic and it is soluble in $\mathrm{NaOH}$ solution, but insoluble in ${\mathrm{NaHCO}}_3$ solution. Phenol also gives violet colour with neutral ${\mathrm{FeCl}}_3$ solution according to the following reaction.