Answer:
An ionic bond is formed between the two atoms
Note: The missing figure in the question is found in the attachment below
Step-by-step explanation:
Ionic bonding is a type of bonding which involves the transfer of electrons from from atom to another resulting in the formation of positive and negative ions.
The two atoms in A are a magnesium atom and and an oxygen atom.
The magnesium atom possesses two valence shell electrons which are transferred to the oxygen atom which has six valence shell electrons.
The transfer of two electrons from magnesium atom to oxygen atom makes it to become a positive ion with a charge of +2.
The oxygen atom receiving two extra electrons turns it to a negative ion with a charge of -2.
Electrostatic forces of attraction then attracts the two oppositely charged ions to each other, thereby forming an ionic bond between them.