Answer: similar, energy
Explanation: (edmentum answer) Several of the elements in period 5 have electron configurations with only one electron in the 5s sublevel. That suggests that the next sublevel that electrons typically fill, 4d, is not much higher in energy.
Explanation:
When two small nuclei combine together to form a large nuclei then it is known as nuclear fusion.
When nuclei of two hydrogen atoms fuse together then it results in the formation of a helium atom along with the release of lot of energy. This energy is nuclear energy.
This nuclear reaction is as follows.

Thus, we can conclude that nuclear fusion represents nuclear energy.