Number of isomeric compounds with molecular formula $$\mathrm{C}_{9} \mathrm{H}_{10} \mathrm{O}$$ which (i) do not dissolve in $$\mathrm{NaOH}$$ (ii) do not dissolve in $$\mathrm{HCl}$$. (iii) do not give orange precipitate with 2,4-DNP (iv) on hydrogenation give identical compound with molecular formula $$\mathrm{C}_{9} \mathrm{H}_{12} \mathrm{O}$$ is ____________.