Chemistry

Question Analysis
This question tests the student's ability to apply periodic trends in atomic radius to a set of elements, including an exception for noble gases.

Key Concept Explanation
Atomic radius generally decreases from left to right across a period and increases from top to bottom within a group. 

Step-by-step Solution
1. Identify the elements: Sulfur (S), Chlorine (Cl), Argon (Ar), and Phosphorus (P).
2. Place the elements in their respective positions in the periodic table:
S (Group 16, Period 3)
Cl (Group 17, Period 3)
Ar (Group 18, Period 3)
P (Group 15, Period 3)
3. Apply the trend: Atomic radi...