Which term describes different forms of an element that have the same number of protons but different numbers of neutrons?

• A. Isotopes
• B. Allotropes
• C. Ions
• D. Isomers

Answer: (A)

Verified step by step guidance

1. Understand that the problem is asking for a term that describes different forms of the same element with the same number of protons but different numbers of neutrons.
2. Recall that the number of protons defines the element, so all forms must have the same atomic number.
3. Recognize that variations in the number of neutrons lead to different forms called isotopes.
4. Note that allotropes refer to different structural forms of the same element (like carbon as diamond or graphite), not differences in neutrons.
5. Understand that ions are atoms with different numbers of electrons, and isomers are molecules with the same formula but different arrangements, so these do not fit the description.