Chemistry

Question Analysis
This question tests the student's understanding of the fundamental definition of isotopes and the properties that define them.

Key Concept Explanation
Isotopes of an element have the same number of protons (and thus the same atomic number) but differ in the number of neutrons. This results in different mass numbers but identical chemical properties.

Step-by-step Solution
1. Recall the definition of isotopes.
2. Identify the subatomic particle that remains constant among isotopes of th...