Which pair below describes isotopes of the same element?

• A. 6 protons, 6 neutrons and 7 protons, 6 neutrons
• B. 6 neutrons, 6 electrons and 7 neutrons, 7 electrons
• C. 6 protons, 7 neutrons and 7 protons, 7 neutrons
• D. 6 protons, 6 neutrons and 6 protons, 7 neutrons

Answer: (D)

Verified step by step guidance

1. Recall that isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.
2. Identify the number of protons in each pair, since the proton number defines the element.
3. Check the pairs given: the first pair has 6 protons and 7 protons, which are different elements, so they are not isotopes.
4. The second pair lists neutrons and electrons, but isotopes are defined by protons and neutrons, so this pair is not relevant for isotopes.
5. The last pair has 6 protons with 6 neutrons and 6 protons with 7 neutrons, meaning same element (6 protons) but different neutrons, which fits the definition of isotopes.