Free Nuclear Physics MCQs with Answers
23 Nuclear Physics MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
23 questions · page 3 of 3
21. After 3 half-lives, the remaining fraction of a radioactive sample is:
- A. 1/2
- B. 1/4
- C. 1/8
- D. 1/16
Explanation: Each half life halves the number of undecayed nuclei, so three of them give a half multiplied by a half multiplied by a half, which is one eighth. Decay is exponential, so the fractions multiply rather than the half lives adding in any simple way. After four half lives one sixteenth would remain.
Correct answer: 1/822. The time in which half of the given number of radioactive nuclei decay is known as
- A. 1/2 life of radioactive element
- B. 2/3 life of radioactive element
- C. 1/4 life of radioactive element
- D. 2/5 life of radioactive element
Explanation: The half life is the interval in which half the undecayed nuclei present decay, and because decay is random with a constant probability per nucleus, that interval stays the same however much material remains. Carbon 14 has a half life of about 5730 years and iodine 131 about 8 days. The quantity is a property of the nuclide and cannot be altered by temperature or pressure.
Correct answer: 1/2 life of radioactive element23. The protons in the nucleus of an atom DO NOT exit due to
- A. Electromagnetic force
- B. Gravitational force
- C. Weak nuclear force
- D. Strong nuclear force
Explanation: The strong nuclear force acts over only a few femtometres but far exceeds the electrostatic repulsion between protons at that range, so it is what holds the nucleus together. The electromagnetic force pushes the protons apart and would blow the nucleus open on its own. Gravity is utterly negligible at nuclear scale and the weak force governs beta decay rather than binding.
Correct answer: Strong nuclear force