charge conservation is always valid. Is it also true for mass ?

Explanation

To address the question of whether mass conservation is always valid, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding Charge Conservation**:
- Charge conservation states that the total electric charge in an isolated system remains constant over time. This means that the initial charge (before any interactions) is equal to the final charge (after interactions).
- Mathematically, this can be expressed as:
\[
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