In the following table, the positions of six elements A, B, C, D, E and F are given as they are in the Modern Periodic Table : On the basis of the above table, answer the following questions : (i) Name the element which forms only covalent compounds. (ii) Name the element which is a metal with valency three. (iii) Name the element which is a non-metal with valency three. (iv) Out of B and C, whose atomic radius is bigger and why ? (v) Write the common name for the family to which the elements D and F belong.