22.1 The Nucleus

Which of the following statements correctly describes the relationship between the three nuclear quantities?

• Atomic number equals the mass number plus the neutron number.

• Mass number equals the atomic number plus the neutron number.

• Neutron number equals the mass number plus the atomic number.

• Mass number equals the neutron number minus the atomic number.

The mass number of a given isotope is equivalent to which of the following?

• the precise mass of the nucleus in atomic mass units

• the number of protons in the nucleus

• the number of neutrons in the nucleus

• the number of protons and neutrons in the nucleus

What is the energy associated with the mass of a subatomic particle called?

• internal energy

• rest energy

• nuclear energy

• binding energy

Which of the following statements correctly describes the necessary condition for a nucleus to be stable?

• The number of neutrons must increase more than the number of protons.

• The number of neutrons must equal the number of protons.

• The number of neutrons must increase less than the number of protons.

• Nuclear stability does not depend on the number of neutrons.

What force binds nucleons together in a nucleus?

• gravitational force

• Coulomb force

• strong force

• weak force

Why is the mass of a nucleus different than the sum of the masses of the nucleons that make up the nucleus?

• Some nucleons undergo beta decay, and so increase the nuclear mass.

• Some nucleons undergo beta decay, and so decrease the nuclear mass.

• Part of nucleon mass is converted to binding energy within the nucleus.

• The nucleus absorbs particles not bound to individual nucleons.

The atomic mass of  ⁵²₂₄Cr is 51.940 511 u. What is the mass defect for this isotope? (atomic mass of = 1.007 825 u; m_n 1.008 665 u)

• 0.244 954 u

• 0.489 909 u

• 0.979 818 u

• 1.959 636 u

The mass defect for a particular isotope is 0.466 769 u. What is the binding energy in MeV for the nucleus of this isotope? (c² = 931.49 MeV/u)

• 5.0109 x 10^-4 MeV

• 5.0109 MeV

• 217.40 MeV

• 434.79 MeV

Explain why the number of neutrons required for stability by more-massive nuclei differs from the number of neutrons required for stability by less-massive nuclei.

• More neutrons are needed because protons are larger in more massive nuclei.

• More neutrons are needed to counteract the force of the protons.

• More neutrons are needed to provide more of the strong force that holds nucleons together.

• More neutrons are needed to separate the protons.

Calculate the binding energy of a  ²¹₁₀Ne nucleus. (c² = 931.49 MeV/u; atomic mass of  ²¹₁₀N = 20.993 841 u; atomic mass of  ¹₁H = 1.007 825 u; m_n = 1.008 665 u)

• 16.41 MeV

• 156.97 MeV

• 139.27 MeV

• 167.41 MeV