During reaction between calcium and oxygen valence electrons A. are transferred from atoms of calcium to atoms of oxygen to form Ca+ and O- ions

B. are shared between atoms of calcium and atoms of oxygen

C are transferred from atoms of calcium to atoms of oxygen to form Ca+2 and O-2 ions

D. are transferred from atoms of oxygen to atoms of calcium to form Ca- and O+ ions

C are transferred from atoms of calcium to atoms of oxygen to form Ca+2 and O-2 ion

Explanation:

Calcium is a meta and Oxygen is a non metal. The bond that forms between a metal and a non metal is an ionic bond. In an ionic bond, the metal loses electrons while the non metal gains the electrons; hence there is transfer of electrons.

Calcium belongs to group 2 and oxygen needs 2 more electrons to complete it's electronic configuration.

Calcium would lose two electrons to form Ca+2 and oxygen would gain two electrons to form O-2 ion

The correct option is;

C. are transferred from atoms of calcium to atoms of oxygen to form Ca+2 and O-2 ion