Which statement is true regarding the radioactive isotope uranium-235?

• A. It has 92 protons and 143 neutrons in its nucleus.
• B. It has 235 protons and 92 neutrons in its nucleus.
• C. It is a stable isotope and does not undergo radioactive decay.
• D. It is the most abundant isotope of uranium found in nature.

Answer: (A)

Verified step by step guidance

1. Identify the atomic number and mass number of uranium-235. The atomic number (number of protons) for uranium is 92, and the mass number (total number of protons and neutrons) is 235.
2. Calculate the number of neutrons by subtracting the atomic number from the mass number: \(\text{neutrons} = 235 - 92\).
3. Understand that the number of protons defines the element, so uranium always has 92 protons regardless of the isotope.
4. Recognize that uranium-235 is radioactive, meaning it undergoes radioactive decay, so it is not stable.
5. Recall that uranium-238 is the most abundant isotope of uranium found in nature, not uranium-235.