Final answer:
The most reasonable atomic radius of Cl is 99 pm or 0.99 Å. This measurement represents half of the internuclear distance between the nuclei of two chlorine atoms in the Cl₂ molecule.
Step-by-step explanation:
The most reasonable atomic radius of Cl is 99 pm or 0.99 Å (Angstroms). This measurement represents half of the internuclear distance between the nuclei of two chlorine atoms in the Cl₂ molecule. Chemists use covalent atomic radius as a basis for describing the approximate sizes of atoms, and in the case of chlorine, the covalent atomic radius is 99 pm.