Mass defect and binding energy per nucleon — practice questions

Question 1 · difficulty L1 · recall

Mass defect is the difference between

• A. the sum of free nucleon masses and the actual nuclear mass
• B. nuclear mass and electron mass only
• C. atomic number and mass number
• D. photon mass and proton mass

Question 2 · difficulty L1 · understanding

Binding energy is related to mass defect Δm by

• A. E=Δm/c²
• B. E=Δm c²
• C. E=Δm c
• D. E=c²/Δm

Question 3 · difficulty L2 · understanding

Binding energy per nucleon is

• A. total binding energy multiplied by A
• B. mass defect divided by Z only
• C. total binding energy divided by mass number A
• D. binding energy divided by neutron number always

Question 4 · difficulty L2 · application

A nucleus with larger binding energy per nucleon is generally

• A. less tightly bound
• B. necessarily more radioactive
• C. unbound
• D. more tightly bound

Question 5 · difficulty L3 · application

If mass defect is 0.010 u, the binding energy is approximately

• A. 9.31 MeV
• B. 0.010 MeV
• C. 93.1 MeV
• D. 9310 MeV

Question 6 · difficulty L3 · application

The binding-energy-per-nucleon curve peaks near

• A. hydrogen only
• B. medium-mass nuclei around iron
• C. the heaviest nuclei only
• D. free neutrons

Question 7 · difficulty L4 · analysis

Fusion of light nuclei releases energy when the product has

• A. lower binding energy per nucleon
• B. exactly zero mass defect
• C. higher binding energy per nucleon
• D. more free nucleons than before

Question 8 · difficulty L4 · analysis

Fission of a very heavy nucleus can release energy because the fragments typically have

• A. lower binding energy per nucleon
• B. zero nuclear forces
• C. greater total rest mass
• D. higher binding energy per nucleon than the original nucleus

Question 9 · difficulty L5 · analysis

Two nuclei have the same mass number but different total binding energies. The one with larger total binding energy has

• A. larger binding energy per nucleon
• B. smaller binding energy per nucleon
• C. the same binding energy per nucleon
• D. necessarily fewer protons

Question 10 · difficulty L5 · analysis

Why is nuclear mass smaller than the sum of constituent free-nucleon masses?

• A. Nucleons lose electric charge permanently
• B. Energy is released when the bound state forms, reducing the system's mass-energy
• C. Neutrons disappear inside nuclei
• D. The speed of light changes in nuclei