Nuclear fission and fusion reactions are examples of conversion of `……………..` into `……………..`

Explanation

To solve the question regarding nuclear fission and fusion reactions, we need to identify what is being converted into what during these processes.

### Step-by-Step Solution:

1. **Understanding Nuclear Fission**:
- Nuclear fission is a process where the nucleus of an atom splits into two or more smaller nuclei, along with the release of a significant amount of energy. This process involves the conversion of mass into energy.

2. **Understanding Nuclear Fusion**:
...