Answer : The pair of elements form an ionic bond will be, barium and chlorine.
Explanation:
Ionic bond : It is defined as the bond that is formed by complete transfer of electrons from one atom to another atom.
That means, the atom which looses the electron is known as electropositive atom and the atom which gains the electron is known as electronegative atom.
The ionic bond is usually formed between a metal and a non-metal.
Covalent bond : It is defined as the bond which is formed when sharing of electrons takes place between the atoms.
This is usually formed between two non-metals.
(a) Barium and chlorine
In this pair, barium is a metal and chlorine is a non-metal. So, barium and chlorine will form an ionic bond.
(b) Carbon and chlorine
In this pair, carbon is a non-metal and chlorine is also non-metal. So, carbon and chlorine will form a covalent bond.
(c) Nitrogen and oxygen
In this pair, nitrogen is a non-metal and oxygen is also non-metal. So, nitrogen and oxygen will form a covalent bond.
(d) Carbon and oxygen
In this pair, carbon is a non-metal and oxygen is also non-metal. So, carbon and oxygen will form a covalent bond.
Hence, the pair of elements form an ionic bond will be, barium and chlorine.
