(a) B2O3⟶ oxide of boron (non-metal) :acidic CaO⟶ oxide of calcium (metal) : basic (b) B2O3⟶ oxide of boron (non-metal) : acidic SiO2⟶ oxide of silicon (non-metal) : acidic (c) N2O⟶ oxide of nitrogen (non-metal) : neutral BaO⟶ oxide of barium (metal) : basic (d) CaO⟶ oxide of calcium (metal): basic SiO2⟶ oxide of silicon (non-metal): acidic So, option (b) is the correct answer. B2O3 and SiO2 are being acidic oxide they react with base to give salt and water. B2O3+2NaOH⟶