β⁻ Decay: Neutron to Proton Transformation

Steps:

• Identify β⁻ decay as a weak nuclear process where a nucleus emits an electron to increase its atomic number.
• Recall the fundamental reaction: neutron (n) decays to proton (p), electron (e⁻), and electron antineutrino (ν̄_e).
• Match this to statements: correct one describes neutron-to-proton change with e⁻ and ν̄_e emission.
• Eliminate options with proton-to-neutron (β⁺ decay) or neutrino (wrong particle).

Why A is correct:

• Matches the standard β⁻ decay equation n → p + e⁻ + ν̄_e, conserving charge, baryon number, and lepton number via weak interaction.

Why the others are wrong:

• B: Specifies neutrino instead of antineutrino, violating lepton number conservation.
• C: Describes proton-to-neutron change, which is β⁺ decay, not β⁻.
• D: Combines incorrect proton-to-neutron transformation with wrong neutrino emission.

Final answer: A