How do the isotopes of an element differ from each other?

• A. They have different numbers of protons.
• B. They have different numbers of neutrons.
• C. They belong to different elements.
• D. They have different chemical symbols.

Answer: (B)

Verified step by step guidance

1. Recall that isotopes are atoms of the same element, which means they have the same number of protons. The number of protons defines the element and its chemical properties.
2. Understand that isotopes differ in the number of neutrons in their nuclei. This difference in neutron number changes the atomic mass but not the chemical behavior significantly.
3. Recognize that the chemical symbol and atomic number (number of protons) remain the same for isotopes of an element, so these do not differ.
4. Summarize that isotopes are variants of the same element with identical proton counts but different neutron counts, which affects their mass and some nuclear properties.
5. Therefore, the key difference between isotopes is the number of neutrons, not protons or chemical symbols.