Chemistry

Question Analysis
This question involves energy levels of atomic subshells and electron configuration.
The main focus is on identifying the highest energy subshell that contains electrons in Cl.

Key Concept Explanation
Subshell Energy Order: Following the Aufbau principle, subshell energy increases in the order: 1s < 2s < 2p < 3s < 3p < 4s < 3d...
The highest energy subshell is the last one filled in the electron configuration.

Step-by-Step Solution
1. Cl has 17 electrons; full configuration: 1s²2s²2p⁶3s²3p⁵.
2. List the subshells...