To determine the hybridization of the central atom in each of these molecules, we first need to consider their molecular geometry and bonding characteristics.
a) **HCN (Hydrogen Cyanide)**: The central atom is carbon (C). In HCN, carbon forms one triple bond with nitrogen (N) and a single bond with hydrogen (H). Here, carbon utilizes sp hybridization due to the linear geometry (180° bond angle). So, this has sp hybridization.
b) **SO2 (Sulfur Dioxide)**: The central atom is sulfur (S). In SO2, sulfur has one double bond with oxygen (O) and has a lone pair. The presence of one lone pair and two bonding pairs gives SO2 a bent shape, and the hybridization of sulfur here is sp2.
c) **OCl2 (Oxygen Dichloride)**: The central atom is oxygen (O). In OCl2, oxygen forms two single bonds with chlorine (Cl) atoms and has two lone pairs. This arrangement leads to a bent geometry, and the hybridization of the central atom is also sp3, not sp2.
d) **XeCl2 (Xenon Dichloride)**: The central atom is xenon (Xe). In XeCl2, xenon forms two single bonds with chlorine atoms and has three lone pairs. This structure is linear, which indicates an sp3d hybridization on the central atom.
In summary:
- HCN: sp hybridization
- SO2: sp2 hybridization
- OCl2: sp3 hybridization
- XeCl2: sp3d hybridization
Therefore, out of the four molecules listed, only one of them (SO2) exhibits sp2 hybridization on the central atom.