A scientist performs an experiment in which a radium–226 (Ra–226) atom decays into radon–222 (Rn–222). The scientist concludes that some energy must have been added to the system to cause this reaction to begin. Which would disprove his conclusion?
A) Radium–226 is an unstable isotope of radium.
B) Radon–222 is an unstable isotope of radon.
C) The decay released an alpha particle.
D) The decay released a beta particle and a gamma ray.