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 \( 2,4\text{-DNP} \) (iv) on hydrogenation give identical compound with molecular formula \( \mathrm{C}_9\mathrm{H}_{12}\mathrm{O} \) is _________.
