Match the following : 

1:D; 2:C; 3:B; 4:A

1. Size of nucleus is much smaller than the size of an atom.

2. Mass defect is the difference between the actual atomic mass and the predicted mass calculated by adding the mass of protons and neutrons present in the nucleus. The actual atomic mass is less than the predicted mass calculated by adding the masses of nucleons.

3. In nuclear fusion, two lighter nuclei fuse and make big nuclei. In this, mass defect is converted into energy according to E=mc^2 _. Momentum is conserved

4. In nuclear fission, heavy nuclei split into two or more than two smaller nuclei. In this process, mass is converted into energy according to E=mc2. Momentum is conserved