In atoms with a mass greater than 60 amu, the process where the nuclei fragment or break apart into several smaller nuclei is called a. nuclear fission c. nuclear reactor b. nuclear fusion d. nuclear mass

The appropriate answer is a. nuclear fission. Nuclear fission is the splitting of an atomic nucleus into two smaller nuclei of about the same or equal mass. This process was discovered or documented in the 1930s by Lise Meitner and Otto Hahn. They observed and recorded the phenomenon with uranium-235. Nuclear fission usually occurs in a continuous reaction called a nuclear chain reaction. 

1.from liquid state to gaseous state is evaporation 3.solid to liquid is melting 5. solid to gaseous state is sublimation 6. gas to solid state is decomposition 7. a change of state is known as the states of matters

The answer should be c.