An atom has 10 protons and 10 neutrons. Which of the following is an isotope of this atom?

• A. An atom with 9 protons and 10 neutrons
• B. An atom with 11 protons and 10 neutrons
• C. An atom with 10 protons and 10 electrons
• D. An atom with 10 protons and 11 neutrons

Answer: (D)

Verified step by step guidance

1. Identify the element by its number of protons. Since the atom has 10 protons, it corresponds to the element with atomic number 10, which is neon (Ne).
2. Recall that isotopes are atoms of the same element (same number of protons) but with different numbers of neutrons.
3. Examine each option to see if the number of protons matches 10, because only atoms with 10 protons can be isotopes of the original atom.
4. Check the neutron number in the options that have 10 protons to see if it differs from the original 10 neutrons, which would indicate an isotope.
5. Conclude that the atom with 10 protons and 11 neutrons is an isotope of the original atom because it has the same number of protons but a different number of neutrons.