Which of the following is Lewis acid?

Step-by-step solution

A Lewis acid is a chemical species that can accept a pair of electrons. In BeCl ₂ , the central beryllium atom forms two single covalent bonds with two chlorine atoms. The valence shell of beryllium in this molecule contains only 4 electrons, which means its octet is incomplete. Due to this electron deficiency, BeCl ₂ has a strong tendency to accept electron pairs from other species (Lewis bases) to complete its octet. For example, in the solid state, it forms a polymeric chain structure through coordinate bonding