The ranking from largest to smallest atomic radius is: Po > Te > Se > O.
To rank the atomic radii of O (Oxygen), S (Sulfur), Se (Selenium), Te (Tellurium), and Po (Polonium) from largest to smallest, we can use the periodic table trends. As you move down a group (vertical column), the atomic radius generally increases due to the addition of electron shells.
Based on this trend, the order from largest to smallest atomic radius is:
Po > Te > Se > S > O