binding energy and mass defect

A lithium-7 nucleus (³Li⁷) has a mass of 7.0160 u. It contains 3 protons and 4 neutrons.

Given:

m_p = 1.0073 u, m_n = 1.0087 u, 1 u = 931.5/c² Mev.

What is the binding energy per nucleon?

• 4.80 MeV

• 4.66 MeV

• 4.58 MeV

• 4.93 MeV

Answer explanation

Which nucleus, when fused in pairs, would release the most energy per nucleon?

•  Deuterium (¹H²)

•  Helium-4

• Oxygen-16

•  Iron-56

Given that the binding energy per nucleon for Fe-56 is 8.79 MeV and for U-238 is 7.57 MeV, why does fission of U-238 release energy?

• Binding energy increases

• Mass is gained

• Number of neutrons increases

• Proton number increases

If a nuclear reaction results in a mass loss of 5.5 x 10^-30 kg, what energy is released?

•  4.95 x 10^-13J

•  3.30 x 10^-13J

•  5.00 x 10^-12J

•  1.65 x 10^-12J

Why can’t stars continue fusion beyond iron?

•  Helium is unstable

• Iron fusion absorbs energy

•  Iron is radioactive

• Neutrons are unavailable

A neutral helium-4 atom (₂He⁴) has an atomic mass of 4.0026 u. It contains 2 protons, 2 neutrons, and 2 electrons.

Use the following data:

• Mass of 1 proton = 1.0073 u

• Mass of 1 neutron = 1.0087 u

• Mass of 1 electron = 0.0005 u

What is the mass defect of the helium nucleus?

• 0.0285 u

• 0.0344 u

• 0.0304 u

• 0.0256 u

For two nuclei with A = 60, which has higher binding energy per nucleon?

• One with more protons

• One with fewer protons

• Same for both

• One with more neutrons

What energy in joules corresponds to a mass defect of 0.200 u?

(1 u = 1.493 x 10^-10 J)

• 2.99 x 10^-11 J

• 2.99 x 10^-10J

• 1.86 x 10^-10 J

• 1.00 x 10^-9 J

Which physical principle explains mass defect?

• Conservation of momentum

• Pauli exclusion

• Mass-energy equivalence

• Conservation of charge

Which change decreases the binding energy per nucleon?

• Fusing light nuclei

• Adding a neutron far beyond stability

• Splitting heavy nucleus

• Forming an alpha particle