question_answer 4)

               Use Mendeleev's periodic table to predict the formulae for the oxides of the following elements: K, C, Al, Si, Ba. 

Answer:

Oxygen is a member of group VI A in Mendeleef's periodic table. Its valency is 2. Similarly. the valencies of all the elements listed can be predicted from their respective groups. This can help in writing the formulae of their oxides. (i) Potassium (K) is a member of group IA. Its valency is 1. Therefore, the formula of its is (ii) Carbon (C) is a member of group IV A. Its valency is 4. Therefore, the formula of its isor   (iii) Aluminium (Al) belongs to groups III A and its valency is 3. The formula of its oxide is  (iv) Silicon (Si) is present in group IV A after carbon. Its valency is also 4. The formula oxide is or    (v) Barium (Ba) belongs to group II A and the valency of the element is 2. The formula of oxide of the element is or