Which statement best describes isotopes and how they are similar and different from each other?

• A. Isotopes are atoms of different elements that have the same mass number.
• B. Isotopes are atoms of the same element with different numbers of electrons and the same number of neutrons.
• C. Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
• D. Isotopes are atoms of different elements that have the same number of neutrons but different numbers of protons.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the definition of isotopes. Isotopes are variants of the same chemical element that have the same number of protons but differ in the number of neutrons in their nuclei.
2. Step 2: Recall that the number of protons defines the element, so isotopes must have the same atomic number (number of protons) to be considered the same element.
3. Step 3: Recognize that isotopes differ in their mass number because the mass number is the sum of protons and neutrons, and the neutron count varies among isotopes.
4. Step 4: Eliminate options that describe atoms of different elements or that mention differences in electrons or neutrons without maintaining the same number of protons.
5. Step 5: Conclude that the correct description of isotopes is: atoms of the same element with the same number of protons but different numbers of neutrons.