(a) The non-metals which show disproportionation reaction are N, P, S, Cl, Br and I. (i) $2\mathrm{NO}_{2(\mathrm{aq})} + 2\mathrm{OH}^{-}_{(\mathrm{aq})}$ → ${\mathrm{NO}_2^-}_{(\mathrm{aq})} + {\mathrm{NO}_3^-}_{(\mathrm{aq})} + {\mathrm{H_2O}}_{(\mathrm{l})}$ (ii) $\mathrm{P}_{4(\mathrm{s})} + 3\mathrm{OH}^{-}_{(\mathrm{aq})} + 3\mathrm{H_2O}_{(\mathrm{l})}$ → $\mathrm{PH}_{3(\mathrm{g})} + 3\mathrm{H_2PO_2}^{-}_{(\mathrm{aq})}$ (iii) $\mathrm{S}_{8(\mathrm{s})} + 12\mathrm{OH}^{-}_{(\mathrm{aq})}$ → $4\mathrm{S}^{2-}(\mathrm{aq}) + 2\mathrm{S_2O_3}^{2-}_{(\mathrm{aq})} + 6\mathrm{H_2O}_{(\mathrm{l})}$ (iv) $\mathrm{Cl}_{2(\mathrm{g})} + 2\mathrm{OH}^{-}_{(\mathrm{aq})}$ → $\mathrm{Cl}^{-}_{(\mathrm{aq})} + \mathrm{ClO}^{-}_{(\mathrm{aq})} + \mathrm{H_2O}_{(\mathrm{l})}$ Bromine and iodine give similar reactions as chlorine. (b) The metals which undergo disproportionation reaction are : $\mathrm{Cu}^{+}, \mathrm{Ga}^{+}, \mathrm{In}^{+}$, etc. (i) $2\mathrm{Cu}^{+}_{(\mathrm{aq})}$ → $\mathrm{Cu}^{2+}_{(\mathrm{aq})} + \mathrm{Cu}_{(\mathrm{s})}$ (ii) $3\mathrm{Ga}^{+}_{(\mathrm{aq})}$ → $\mathrm{Ga}^{3+}_{(\mathrm{aq})} + 2\mathrm{Ga}_{(\mathrm{s})}$ (iii) $3\mathrm{In}^{+}_{(\mathrm{aq})}$ → $\mathrm{In}^{3+}_{(\mathrm{aq})} + 2\mathrm{In}_{(\mathrm{s})}$