Question

Choose the correct statement according to the Lewis acid-base concept.

• A. All anions are acids.
• B. Molecules that have vacant d orbitals in the central atom act as acids.
• C. All cations are bases.
• D. Molecules with a complete octet of central atoms act as acids.

Answer 1

The correct option is B Molecules that have vacant d orbitals in the central atom act as acids.

According to the Lewis theory of acid-base reactions; Lewis acids and bases are described as the electron pair acceptors and the electron pair donors respectively.
- Thus, we can say that a Lewis base can donate a pair of electrons to a Lewis acid to form a product containing a coordinate covalent bond.
- Lewis acids are the chemical species that have empty orbitals and can accept electron pairs from the Lewis bases. These chemical species can donate an electron pair to a given Lewis acid to form a “Lewis adduct”. Therefore, we conclude that molecules in which a central atom has vacant orbitals will act as acid.
So, the correct answer is option (b).