Radioactive decay accounting — In which decay process does the atomic number NOT decrease?

Introduction:
Tracking atomic number changes in nuclear decay is essential for balancing nuclear equations. Some processes reduce the proton number, while others increase it or leave it unchanged.

Given Data / Assumptions:

• Atomic number Z represents the number of protons.
• We consider electron capture, β−, α, and β+ decays.

Concept / Approach:
Determine the sign of change in Z for each decay mode: electron capture and β+ both convert a proton to a neutron (Z decreases by 1). α emission removes two protons (Z decreases by 2). β− converts a neutron to a proton (Z increases by 1), so Z does not decrease.

Step-by-Step Solution:
Electron capture: p + e− → n + ν → Z decreases by 1.β+ emission: p → n + β+ + ν → Z decreases by 1.α emission: loss of 2 protons → Z decreases by 2.β− emission: n → p + β− + ν̄ → Z increases by 1, so it does not decrease.

Verification / Alternative check:
Nuclear charts confirm daughter nuclides after β− decay lie one element higher (Z+1).

Why Other Options Are Wrong:

• Electron capture, α, and β+ all reduce Z.

Common Pitfalls:
Mixing up β− and β+ effects; forgetting that α emission reduces Z by two.

Final Answer:
β-emission (beta minus)