Which one of the following contains all Lewis acids ?

According to the Lewis definition, an acid is a species capable of accepting an electron pair, while a base is an electron pair donor. Lewis acids typically include electron-deficient molecules and metal cations. Boron trifluoride (BF3) and Aluminium chloride (AlCl3) are classic examples of Lewis acids because the central atoms have incomplete octets and can accept electron pairs [1]. Metal cations like Co3+ act as Lewis acids because their positive charge allows them to attract and accept electron pairs from ligands. In contrast, molecules like NH3 and H2O, and anions like OH- and F-, possess lone pairs of electrons, making them Lewis bases. Option 1 is the only set containing exclusively Lewis acids (AlCl3, Co3+, and BF3), whereas the other options include Lewis bases such as ammonia, water, or fluoride ions.

Sources

1. [1] https://en.wikipedia.org/wiki/Lewis_acid_catalysis