Evidence shows that interstellar bodies are moving away from earth ,some faster than others, which best suggests that the universe

Ithink about 50 % of an original isotope's number of atoms remain

Small amounts of matter are converted intolarge amounts of energy occurs in both fusion and fission reactions. they are nuclear reactions where a change in the identity or characteristics of an atomic nucleus results when it is bombarded with an energetic particle, as in fission, fusion, or radioactive decay.