What is nuclear fusion ? Write its one example and one use of this reaction.

Explanation

### Step-by-Step Solution:

1. **Definition of Nuclear Fusion**:
Nuclear fusion is a process in which two lighter atomic nuclei combine to form a heavier nucleus. During this process, a significant amount of energy is released.

2. **Example of Nuclear Fusion**:
A common example of nuclear fusion is the fusion of two deuterium nuclei (isotopes of hydrogen). When two deuterons (1H²) fuse, they form a helium nucleus (4He) along with the release of energy. The reaction can be represented as:
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