Which decay process emits gamma radiation without changing the atomic number or mass number?

Which decay process emits gamma radiation without changing the atomic number or mass number?

• A. Gamma emission
• B. Electron capture
• C. Beta decay
• D. Alpha decay

Answer: (A)

Gamma emission is when a nucleus in an excited state releases excess energy as a gamma photon and settles to a lower energy state, without losing or gaining any nucleons or protons. Because gamma rays carry no mass and no electric charge, the nucleus’ composition stays the same—the atomic number and the mass number do not change. Other decay modes involve changing the number of protons or nucleons: alpha decay ejects a helium nucleus, reducing both mass and atomic numbers; beta decay converts a neutron to a proton (or a proton to a neutron, in the case of beta-plus decay), changing the atomic number but keeping the mass number the same; electron capture also lowers the atomic number by converting a proton into a neutron. Since this question specifies gamma radiation with no change to Z or A, gamma emission is the correct process.

Gamma emission is when a nucleus in an excited state releases excess energy as a gamma photon and settles to a lower energy state, without losing or gaining any nucleons or protons. Because gamma rays carry no mass and no electric charge, the nucleus’ composition stays the same—the atomic number and the mass number do not change.

Other decay modes involve changing the number of protons or nucleons: alpha decay ejects a helium nucleus, reducing both mass and atomic numbers; beta decay converts a neutron to a proton (or a proton to a neutron, in the case of beta-plus decay), changing the atomic number but keeping the mass number the same; electron capture also lowers the atomic number by converting a proton into a neutron. Since this question specifies gamma radiation with no change to Z or A, gamma emission is the correct process.