What is true about sulfur trioxide in the context of Lewis acidity?

Sulfur trioxide (SO₃) is recognized as a strong Lewis acid due to its ability to accept electron pairs. The sulfur atom in sulfur trioxide has an incomplete octet and can effectively receive electrons from Lewis bases. This property is enhanced by the molecular geometry and the presence of electronegative oxygen atoms, which draw electron density away from the sulfur. Consequently, this leads to an increased susceptibility of the sulfur atom to accept electrons, categorizing SO₃ as a strong Lewis acid.

In Lewis acid-base theory, a Lewis acid is defined as a substance that can accept a pair of electrons, while a Lewis base donates a pair of electrons. Given sulfur trioxide’s strong tendency to react with various Lewis bases, it demonstrates its behavior as a Lewis acid. This ability to form adducts with bases, such as water to produce sulfuric acid, underscores its acidenic character in chemical reactions.

The other concepts in the alternatives do not align with the established behavior of sulfur trioxide as strongly as the notion of it being a strong Lewis acid does. While sulfur trioxide does not behave as a Lewis base or form particularly weak acids, its proficiency in accepting electron pairs is what makes it a key player in several acid-base