Chemistry

Question Analysis
This question involves comparing atomic radii of elements in the same group.
The main focus is on the basic trend of atomic radius down a group of the periodic table.

Key Concept Explanation
Atomic radius increases as you move down a group because each element has one more full electron shell than the one above it.

Step-by-Step Solution
1. Identify the group: He, Ne, Ar, Kr are all in Group 18 (noble gases).
2. Apply the group trend: Atomic radius gets larger from top to bo...