Which of the following isotopes has the greatest number of protons?

• A. O-18
• B. U-238
• C. N-15
• D. C-14

Answer: (B)

Verified step by step guidance

1. Recall that the number of protons in an isotope is equal to the atomic number of the element, which is unique for each element and does not change between isotopes.
2. Identify the elements given: Oxygen (O), Uranium (U), Nitrogen (N), and Carbon (C).
3. Look up or recall the atomic numbers for each element: Oxygen has 8 protons, Uranium has 92 protons, Nitrogen has 7 protons, and Carbon has 6 protons.
4. Compare the atomic numbers to determine which isotope has the greatest number of protons.
5. Conclude that the isotope with the greatest number of protons is the one with the highest atomic number, which is Uranium-238 (U-238).