Question 1

All nuclei of a given element have the same number of neutrons.

Accepted Answer

The nuclei of a given element have the same number of protons, but the number of neutrons can vary, resulting in different isotopes of the element.

Question 2

A fusion reaction generates energy by combining lighter nuclei into a heavier nucleus, plus additional particles.

Accepted Answer

Fission reactions, on the other hand, generate energy by splitting a heavy nucleus into lighter nuclei.

Question 3

Quarks can only have a charge of +(2/3)e or -(1/3)e, while antiquarks can only have charges of -(2/3)e or +(1/3)e.

Accepted Answer

This statement is true. Quarks and antiquarks have fractional electric charge and can only have specific values of that charge, which are +(2/3)e, -(1/3)e, -(2/3)e, or +(1/3)e.

Question 4

The density of a nucleus (to a reasonable approximation) is independent of the mass number.

Accepted Answer

The density of a nucleus is determined by the strong nuclear force that holds the protons and neutrons together. This force acts over a very short range, and is relatively constant in value, hence the density of a nucleus is independent of its mass number.

Question 5

The Sun is powered by the proton-proton cycle.

Accepted Answer

The proton-proton cycle is the process through which the Sun (and other stars) produces energy by converting hydrogen into helium. This process is what powers the Sun.

Question 6

The competition between the electrostatic force between the protons in a nucleus and the strong nuclear force determines whether a nucleus is stable.

Accepted Answer

The electrostatic force between the positively charged protons in the nucleus causes an inward pull towards the center of the nucleus, which can cause it to become unstable if it is too large. The strong nuclear force, which holds the nucleus together, must be strong enough to counteract the electrostatic force in order for the nucleus to remain stable. Therefore, the competition between these two forces determines whether a nucleus is stable or not.

Question 7

Particles made up of two quarks must consist of a quark-antiquark pair.

Accepted Answer

Particles made up of two quarks must consist of a quark-antiquark pair because quarks always come in pairs, with one quark having a positive charge and the other having a negative charge.

Question 8

Gravity waves are produced when a mass accelerates.

Accepted Answer

Gravity waves, also known as gravitational waves, are created when a massive object undergoes acceleration or deceleration. This disturbance in space-time causes ripples to propagate through the Universe, which can be detected by sensitive instruments like the Laser Interferometer Gravitational-Wave Observatory (LIGO). Examples of events that can produce gravity waves include the collision of two black holes, the explosion of a supernova, and the acceleration of neutron stars.

Question 9

The radius of a nucleus is proportional to what power of the mass number?

Accepted Answer

The radius of a nucleus is proportional to the cube root of the mass number. This is because the nucleus is made up of nucleons (protons and neutrons), and as the number of nucleons increases, the radius of the nucleus increases. The volume of a sphere (which is proportional to the radius cubed) increases with the cube of the radius, so the radius is proportional to the cube root of the mass number.

Question 10

One type of event that may generate gravity waves of sufficient strength to be detected with current equipment is the death spiral of a neutron star as it plunges into a black hole.

Accepted Answer

This is true. The death spiral of a neutron star as it is consumed by a black hole is one example of an astrophysical event that can create strong gravitational waves which can be detected by current equipment such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo observatory.

Question 11

A moderator is inserted into a fission reaction to absorb neutrons and prevent additional fissions.

Accepted Answer

A moderator is used in a fission reaction to slow down neutrons, not absorb them, to increase the likelihood of further fission reactions.

Question 12

The nuclei of different isotopes of a given element have the same number of

Accepted Answer

Isotopes of a given element have the same number of protons, which is a defining characteristic of the element. The number of neutrons may vary between isotopes, which affects their atomic mass, but the number of protons is always constant. Nucleons refers to both protons and neutrons, so while it is true that isotopes of a given element have the same number of nucleons, this is not the best choice because it is not specific to protons. Electrons and positrons are not found in the nucleus, so these choices are incorrect.

Question 13

Photons associated with the magnetic field used in magnetic resonance imaging have considerably less energy than the photons used in CT scans.

Accepted Answer

The photons used in magnetic resonance imaging have energies in the radiofrequency range, which are considerably less than the X-ray photons used in CT scans.

Question 14

The proton is slightly more massive than the neutron.

Accepted Answer

The neutron is slightly more massive than the proton.

Question 15

The force between two quarks increases with separation.

Accepted Answer

The force between two quarks, described by the strong interaction or color force, increases as they move apart due to the property of confinement in quantum chromodynamics (QCD).

Question 16

What combination of quarks produces a proton and what are the electric charges on these quarks, expressed in terms of e?

Accepted Answer

The answer of What combination of quarks produces a proton...

Question 17

The atomic number is equal to the number of what particles in the nucleus?

Accepted Answer

The atomic number is equal to the number of protons in the nucleus of an atom.

Question 18

The mass number is equal to the number of what particles in the nucleus?

Accepted Answer

The mass number is the total number of nucleons, which includes both protons and neutrons, in the nucleus.

Question 19

The strong nuclear force acts only on neutral particles.

Accepted Answer

The strong nuclear force acts only on particles that carry "color" charge, which includes protons and neutrons (which are not neutral particles).

Question 20

What combination of quarks produces a neutron and what are the electric charges on these quarks, expressed in terms of e?

Accepted Answer

The answer of What combination of quarks produces a neutron...

Quiz 32: Nuclear Physics and Nuclear Radiation