Label the hydrophilic and hydrophobic parts in the following compounds.
$(i)$ $CH_3(CH_2)_{10}CH_2OSO_3^-Na^{+}$
$(ii)$ $CH_3(CH_2)_{15}N^{+}(CH_3)_3Br^{-}$
$(iii)$ $CH_3(CH_2)_{16}COO(CH_2CH_2O)_nCH_2CH_2OH$

(N/A) The molecules are surfactants,which contain a long non-polar hydrocarbon chain (hydrophobic part) and a polar or ionic head group (hydrophilic part).
$(i)$ $CH_3(CH_2)_{10}CH_2-$ is the hydrophobic part and $-OSO_3^-Na^+$ is the hydrophilic part.
$(ii)$ $CH_3(CH_2)_{15}-$ is the hydrophobic part and $-N^{+}(CH_3)_3Br^-$ is the hydrophilic part.
$(iii)$ $CH_3(CH_2)_{16}-$ is the hydrophobic part and $-COO(CH_2CH_2O)_nCH_2CH_2OH$ is the hydrophilic part.