The central atoms/ions in the coordination compounds are referred as _____.

Lewis acid

The correct answer is Option (2) → Lewis acid

The central atoms or ions in coordination compounds are referred to as Lewis acids.

Lewis Acid: A Lewis acid is a species that can accept a pair of electrons. In a coordination compound, the central metal atom or ion has empty orbitals and can accept electron pairs from the ligands (which are Lewis bases). This interaction forms coordinate covalent bonds.

Lewis Base: Ligands are typically Lewis bases because they donate electron pairs to the central metal ion.

Brønsted Acid: A Brønsted acid is a proton (H⁺) donor, which is not directly relevant to coordination chemistry.

Brønsted Base: A Brønsted base is a proton (H⁺) acceptor, which also does not apply to the role of the central metal atom in coordination chemistry

Summary:

The central atom/ion in coordination compounds acts as a Lewis acid because it accepts electron pairs from the ligands.