Beta-plus decay emits a positron and neutrino

Steps:

• Identify the decay type: Boron (Z=5) to beryllium (Z=4) decreases atomic number by 1, indicating beta-plus (β+) decay.
• Recall β+ process: A proton converts to a neutron, emitting a positron (β+ particle) and a neutrino to conserve energy, lepton number, and charge.
• Confirm particles: The β particle is the positron; the additional particle is the neutrino.
• Rule out alternatives: No neutron or electron emission occurs in this process.

Why C is correct:

• In β+ decay, the reaction p → n + e+ + ν_e requires a neutrino to balance lepton number and conserve momentum, per the weak interaction law.

Why the others are wrong:

• A: Antineutrino is emitted in β- decay, not β+.
• B: Electron is the β- particle, absent in β+ decay.
• D: Neutron emission would change mass number without altering Z this way.

Final answer: C