The atoms of different phosphorus isotopes _____.

• A. have the same number of protons but different numbers of neutrons
• B. have different numbers of protons and electrons
• C. have different chemical properties due to different numbers of protons
• D. have identical mass numbers

Answer: (A)

Verified step by step guidance

1. Recall that isotopes are atoms of the same element that have the same number of protons but differ in the number of neutrons.
2. Since the number of protons defines the element, all isotopes of phosphorus must have the same number of protons (which is 15 for phosphorus).
3. The difference in isotopes comes from the number of neutrons, which affects the mass number but not the chemical properties significantly.
4. Therefore, isotopes have the same number of protons but different numbers of neutrons, leading to different mass numbers.
5. This means options stating different numbers of protons or identical mass numbers are incorrect, and the correct description is that isotopes have the same number of protons but different numbers of neutrons.