Answer 1

(a) An element X from group 2 has a valency of 2. An element Y from group 16 has a valency of 2. As both the elements are divalent, an atom of X combines with an atom of Y to form a compound with the formula XY.

(b) The nature of the bond in the compound is ionic, since the element X is a metal as it is from group 2. The element Y is a non-metal as it is from group 16. When a metal combines with a non-metal, a transfer of electrons takes place and an ionic bond is formed.