Chemistry

Question Analysis
This question evaluates the student's understanding of shorthand notation for electron configurations, which uses the symbol of a noble gas to represent the filled inner electron configuration.

Key Concept Explanation
Shorthand notation simplifies the electron configuration by using the symbol of the nearest noble gas with a lower atomic number to represent the filled inner shells. For potassium (K, atomic number 19), the nearest noble gas is argon (Ar, atomic number 18).

Step-by-step Solution
1. Identify the nearest noble gas with a lower atomic number: Argon (Ar, atomic number 18).