AIIMS 2018 Chemistry Molecular Structure MCQ Question

Selenium (Se) forms halides such as SeCl₂, SeBr₂, and SeI₂, each of which contains at least one lone pair of electrons on the selenium atom, contributing to its ability to form covalent bonds with halogens. In contrast, chromium (Cr) typically forms halides like CrCl₃ and CrF₆, which do not possess lone pairs due to the complete utilization of its d-orbitals in bonding. Nitrogen (N) forms halides such as NH₃ and NF₃, but in these cases, the lone pair is involved in bonding rather than being present in the halides themselves. Sulfur (S) can form halides like SF₆ and SCl₂, but not all of its halides contain lone pairs; for example, SF₆ has no lone pairs on sulfur.