The findings of henri becquerel and the curies to discredit what notion held for a very long time?

The findings of Henri Becquerel and the curies have a significant effect in the field of radio activity.

Henri is considered as the father of radioactivity.He was the first one conducted experiment on the radioactivity and describe the nature of alpha and beta particles with gamma radiations.Before him, it was considered that every nuclei is stable and does not undergo decay.

The Curie couple conducted experiment on artificial radioactivity and invented radium by artificial transmutation.

Hence the findings of Henri and the curie helped to credit the notion that matter is radioactive in nature and decays with the course of time.

conservation of mass

mass before something happens = mass afterwards