Study the following table in which positions of six elements A, B, C, D, E and F are shown 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 D and E, which is bigger is size and why ?
(v) Write the common name for the family to which the elements C and F belong.

Explanation

(i) Element E will form covalent compounds by sharing its four valence electrons.
(ii) Element D is a metal with valency three.
(iii) Element B is a non-metal with valency three.
(iv) We know that the size of elements decreases on moving left to right in a period. Therefore, element D is greater than element E.
(v) The name of the family to which elements C and F belong is the noble gas family (group 18).