Question

which of the following atoms is the largest?
k
na
rb
cs
li

Explanation:

Atomic radius increases down a group in the periodic table. These elements (Li, Na, K, Rb, Cs) are all in Group 1 (alkali metals). As we move down the group from Li (atomic number 3) to Cs (atomic number 55), the number of electron shells increases. More electron shells mean a larger atomic radius.

Answer:

Cs