The ionic compound, CaO, is composed of which of the following pairs of ions?

Question

? 1 Ca2+ ion and 1 O2- ion
? 1 Ca+ ion and 1 O- ion
? 1 Ca2+ ion and 2 O- ions
? 1 Ca2- ion and 1 O2+ ion
? 1 Ca3+ ion and 3 O3- ions

Answer 1

The ionic compound CaO is composed of the following pairs of ions:

• 1 Ca²⁺ ion and 1 O²⁻ ion

Calcium (Ca) typically forms a 2+ charge when it loses two electrons, resulting in the Ca²⁺ ion. Oxygen (O), on the other hand, typically forms a 2− charge when it gains two electrons, resulting in the O²⁻ ion. Therefore, the correct answer is:

• 1 Ca²⁺ ion and 1 O²⁻ ion