(i) Element E is present in Group 14. It has a valency of four. Thus, among the given elements, it forms only covalent compounds. (ii) Element B is present in Group 13. Thus, among the given elements, it is a metal with valency three. (iii) Element C is present in Group 15. It is a non-metal with five valence electrons. Thus, it has a valency of three. (iv) Elements B and C are present in period 2 of the periodic table. On going from left to right in the periodic table, the atomic radii of elements decrease due to increase in effective nuclear charge that pulls the valence electrons close to the nucleus. Thus, out of B and C, the atomic radius of B is bigger. (v) Elements D and F are present in Group 18 of the periodic table. They belong to the family of inert/noble gases.