What is the product of beta decay of carbon-14?

• A. A heavier isotope of nitrogen.
• B. C-14 becomes this when it undergoes beta decay.
• C. The chemical symbol for nitrogen-14.
• D. An isotope produced by the fusion of carbon.

Answer: (B)

Beta decay changes a neutron into a proton inside the nucleus, emitting an electron and an antineutrino. The mass number stays the same while the atomic number increases by one. For carbon-14 (six protons, mass number 14), converting a neutron to a proton gives seven protons and A = 14, which is nitrogen-14. So the product is the nitrogen-14 isotope (14N). This is the most precise way to state what carbon-14 becomes. It’s not a fusion product or just a symbol—the actual product is the nitrogen-14 nucleus.