The correct matches are as follows:
1. first nuclear reactor
Fermi - an italian physicist who made the first nuclear reactor
2. 1/0 η
atomic mass
3. decaying nuclei
fission - nuclear reaction from a heavy elements to lighter elements
4. number of neutrons and protons
neutron
5. builds heavier elements
fusion - nuclear reaction from two or more elements to a heavier element
6. discovered radioactivity
Curie
7. unit of radiation
Becquerel