question_answer 88)

    An element forms an oxide A2O3 which is acidic in nature. Identify A as a metal or non-metal.              

Answer:

                    Oxides of non-metals are acidic in nature while those of metals are basic. As the element A forms an acidic oxide, therefore, A must be a non-metal. Also it should have + 3charge, i.e., it should have 3 valence electrons. Therefore, A is boron, (electronic configuration is 2, 3) and its oxide is.