(i) InBCl₃, Boron has 6 electrons in it is outermost orbital and has a vacant p orbital. Thus, it is an electron-deficient compound.

Hence, it acts as Lewis acid and accepts a lone pair of electrons.

(ii) AlCl3 is an electron-deficient compound. Aluminum has three electrons in its valence shell so it forms a covalent compound with chlorine i.e. it forms three single bonds with chlorine.

The octet of Al is not complete by forming such bonds. Thus it can form a coordinate bondto complete its octet.

Hence, AlCl₃ acts as a Lewis acid.