Radiation Safety Practice Exam

Which two isotopes represent the same element?

1. 1 and 2

2. 2 and 3

3. 3 and 4

4. 1 and 4

The correct answer is: 2 and 3

The correct answer indicates that isotopes 2 and 3 represent the same element. Isotopes of an element differ in the number of neutrons in their nuclei, which results in varying atomic masses. However, they must have the same number of protons, as the number of protons defines the element itself. When identifying isotopes, it's essential to recognize that they all share the same atomic number (protons) but may have different mass numbers (the sum of protons and neutrons). This allows them to be classified as different isotopes of the same element. In this context, isotopes 2 and 3 fulfill these criteria by having the same number of protons but differing neutron counts. Understanding isotopes is crucial in fields such as chemistry and nuclear physics, particularly in applications involving radioactive decay, nuclear reactions, and radiometric dating, among others.