Alpha radiation emits helium nuclei

Steps:

• Recall that radioactive decay involves alpha, beta, or gamma radiation.
• Identify alpha particles as the heaviest type, consisting of two protons and two neutrons.
• Note that this composition matches a helium nucleus, which has the same structure.
• Confirm alpha radiation is particulate, not electromagnetic like gamma rays.

Why B is correct:

• By definition, alpha particles are helium-4 nuclei (two protons and two neutrons) ejected at high speed during decay.

Why the others are wrong:

• A: Protons alone would be hydrogen nuclei, not alpha particles.
• C: Microwaves are electromagnetic waves, not ionizing radiation from nuclei.
• D: Radio waves are low-energy electromagnetic waves, unrelated to nuclear decay.

Final answer: B