An element X is in group 2 of the periodic table:
(a) What will be the formula of its chloride?
(b) What will be the formula of its oxide?

An element X is in group 2 of the periodic table. Therefore, the valency of X is 2.

(a) Chlorine has 7 valence electrons. Therefore, the valency of chlorine Cl is 1, that is, (8 - 7). Hence, the ionic compound is XCl₂.

(b) Oxygen has 6 valence electrons and needs 2 more electrons to complete its octet. Therefore, the valency of oxygen O is 2, that is, (8 - 6). Hence, the ionic compound is XO.