Universal Conservation in Beta Decay

Steps:

• Recall beta decay includes beta minus (neutron → proton + electron + antineutrino) and beta plus (proton → neutron + positron + neutrino).
• Note that particle emissions and nuclear changes differ between beta minus and beta plus.
• Identify conservation laws: mass-energy, nucleon number (A), and charge are always preserved.
• Test each statement for applicability to all beta decays.

Why C is correct:

• Mass-energy conservation, per Einstein's E=mc², holds in every nuclear reaction, including beta decay, balancing total energy before and after.

Why the others are wrong:

• A: Antineutrino is emitted only in beta minus decay, not in beta plus.
• B: Neutron-to-proton change occurs in beta minus; beta plus reverses it (proton to neutron).
• D: Nucleon number A remains constant, as beta decay changes Z but not A.

Final answer: C