A substance that donates a pair of electrons to form coordinate covalent bond is called-

Correct option is A

The correct answer is (a) Lewis-base.
· A Lewis base is a substance that donates a pair of electrons to form a coordinate covalent bond with a Lewis acid, which accepts the electron pair.
· In this interaction, the Lewis base provides the electrons needed to form the bond.
Information Booster:
· Bronsted-Lowry acid: A substance that donates protons (H⁺) in a reaction.
· Lewis acid: A substance that accepts a pair of electrons to form a coordinate covalent bond.
· Bronsted-Lowry base: A substance that accepts protons (H⁺) in a reaction.