NAPT - Navy Advanced Programs Atomic and Nuclear Physics Questions and Answers

Question 1

An atom of Uranium-238 (²³⁸U) and an atom of Uranium-235 (²³⁵U) both have 92 protons. Which of the following best describes their relationship?

Accepted Answer

They are isotopes of the same element.

Answer

They are isobars of different elements.

Answer

They are different elements with similar properties.

Answer

They are isotones with the same neutron number.

Question 2

A radioactive source is placed in front of a Geiger counter. A single sheet of paper placed between the source and detector has no significant effect on the count rate. However, when a 5 mm thick sheet of aluminum is added, the count rate drops to nearly zero. What is the primary type of radiation being emitted?

Accepted Answer

Beta particles

Answer

Alpha particles

Answer

Gamma rays

Answer

Neutrons

Question 3

A sample of a radioactive isotope has a half-life of 20 days. If the initial sample contains 400 grams of the isotope, how much of the original isotope will remain after 60 days?

Accepted Answer

50 grams

Answer

200 grams

Answer

100 grams

Answer

25 grams

Question 4

Which statement accurately describes the process of nuclear fission as it is utilized in a nuclear power reactor?

Accepted Answer

A heavy nucleus, such as uranium-235, splits into two or more lighter nuclei after absorbing a neutron, releasing a large amount of energy and more neutrons.

Answer

Two light nuclei combine under extreme temperature and pressure to form a heavier nucleus, releasing energy.

Answer

An unstable nucleus spontaneously emits a high-energy photon (gamma ray) to move to a lower energy state.

Answer

A neutron in an unstable nucleus transforms into a proton, emitting an electron (beta particle).

Question 5

The mass of a stable atomic nucleus is always slightly less than the sum of the masses of its individual, separate protons and neutrons. What is this difference in mass, known as the 'mass defect,' converted into?

Accepted Answer

Nuclear binding energy holding the nucleons together.

Answer

The kinetic energy of the orbiting electrons.

Answer

Heat that is immediately radiated away from the nucleus.

Answer

Antimatter particles that are instantly annihilated.

Question 6

When an atom of Carbon-14 (¹⁴C), which has 6 protons and 8 neutrons, undergoes beta-minus decay, what is the resulting nucleus?

Accepted Answer

Nitrogen-14 (¹⁴N)

Answer

Boron-14 (¹⁴B)

Answer

Carbon-12 (¹²C)

Answer

Carbon-13 (¹³C)