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 question `:`
(i) Name the element which form 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 in size and why ?
(iv) Write the common name for the family to which the elements C and F belongs.

Explanation

(i) E
(ii) D
(iii) B
(iv) D is bigger in size because as we move from left to right in a period, the size of the atom decreases as positive charge increases but the number of sheels remains the same. Thus the electrons are pulled in more closed to the nucleus.
(v) Noble gases.