What is packing fraction?

1. What is packing fraction? How can packing fraction predict the stability of a nucleus?

2. calculate the packing fraction for hydrogen 1, argan 40 and oxygen 16 ,having the isotopic mass 1.0078,39.9 7 12 and 16 respectively.

3. What is the relation between packing fraction and nuclear stability?

4. What is binding energy?