Multiple choice Which one of the following was used in Neutron discovery by Chadwick? 3Li7 4Be9 6C13 7N15 Reveal answer Fill a bubble to check yourself B Correct answer Explanation James Chadwick discovered the neutron in 1932 using beryllium-9 bombarded with alpha particles from polonium. The nuclear reaction was ⁴He₂ + ⁹Be₄ → ¹²C₆ + ¹n₀. This produced neutral radiation that was identified as neutrons.