Predict the formula for a compound made from x2 + and y2-

A compound is composed of a cation which is positively charged ion and an anion that is the negatively charged ion. In this case, when a compound is formed, an exchange of numbers of charges takes place and here the numbers are same so they cancelled with each other and compound with formula XY is formed.

we take the reaction of Ca and Oxygen here.

Calcium Ca⁺² and O⁻² reacts with each other a compound with formula CaO is formed.