The elements `X,Y` and `Z` belong to groups 2,14 and 16 respectively of the periodic table.
(a) Which two elements will form covalent bond?
(b) Which two elements will form an ionic bond?

Explanation

Let us write down the above given data more clearly as follows:
(a) We know that a covalent bond is formed between two non-metal elements. Now, out of elements `X,Y` and `Z` the element `Y` (of group 14) and element `Z` (of group 16) are non metals. Thus, the elements `Y` an `Z` will form covalent bonds.
(b) An ionic bond is formed betwen a metal and a non metal. Now, out of the above given elements, the element `X` (of group 2) is a metal and element `Z` (of group 16) is a non-metal. Thus, the elements `X` and `Z` will form an ionic bond. Please note that though the element `Y` belonging to group 14 is also non-metal (like carbon) but it usually does not form ionic bonds.
We are non in a position to anser the following questions: