Final answer:
Radon (Rn) has the largest atomic radius among the elements He, Ne, Ar, Kr, and Xe in the 8th column of the periodic table.
Step-by-step explanation:
The element in the 8th column of the periodic table that has the largest radius is Rn (Radon). This can be deduced from the fact that atomic radii increase as you move down a column (or group) in the periodic table. The trend of atomic size across the periodic table generally shows that the largest atoms are found in the lower left corner, while the smallest atoms are in the upper right corner. Considering this, in the 8th column, which comprises the noble gases, Radon, being the lowest element in the group, will have the largest atomic radius compared to the other elements listed (He, Ne, Ar, Kr, Xe).