SAT Subject Physics Practice Question 469: Answer and Explanation
15. Protons are found in the nucleus of the atom. The nuclear protons with the greatest mass are located
A. in the hydrogen atom.
B. in the carbon atom.
C. in the iron atom.
D. in the radon atom.
E. in the uranium atom.
Correct Answer: A
The correct answer is (A). Due to the mass that is converted in the nucleus (mass defect) to hold the protons together in the nucleus, the proton does not have the same mass when it is inside the nucleus as it has outside the nucleus. The hydrogen proton is the proton that is least affected because it is the only proton in the hydrogen atom.