Answer :
The statement that best explains why mass is not conserved in a nuclear change is that; "some of the matter is converted to energy".
In a nuclear reaction, mass is converted to energy. This is the energy that is given out when a new nuclide is formed during a nuclear reaction.
Generally, the scheme of a nuclear reaction is; Parent nucleus + Bombarding particle -------> Daughter nuclei + product particles + energy. This energy is obtained when mass is lost from left toi right in the reaction.
Hence, the correct answer is; some of the matter is converted to energy".
Learn more: https://brainly.com/question/13440572