Radioactive emissions — The atomic number of a nuclide remains unchanged during the emission of which type of radiation?

Introduction:
Radioactive decay can change a nuclide’s atomic number Z (proton count) or only its energy state. Recognizing which emissions alter Z is fundamental in nuclear chemistry and reactor physics.

Given Data / Assumptions:

• Alpha (α) emission ejects a helium nucleus (2 protons, 2 neutrons).
• Beta (β) emission involves a neutron–proton conversion (β− increases Z by 1; β+ or electron capture decreases Z by 1).
• Gamma (γ) emission is a photon emitted as the nucleus relaxes from an excited state.

Concept / Approach:
Only emissions that change the number of protons alter the atomic number. Gamma emission removes nuclear excitation energy without changing proton or neutron counts.

Step-by-Step Solution:
α: Z decreases by 2 → changes atomic number.β−: Z increases by 1; β+: Z decreases by 1 → changes atomic number.γ: Z unchanged; only energy state changes.Therefore, γ emission leaves atomic number unchanged.

Verification / Alternative check:
Nuclear reaction equations for γ emission show identical nuclide symbols before and after, with an added γ photon.

Why Other Options Are Wrong:

• α and β emissions explicitly change Z.
• 'α & β' doubles down on changes to Z and is incorrect.

Common Pitfalls:
Confusing internal conversion electrons (atomic process) with β decay; mixing β− and β+ effects on Z.

Final Answer:
γ