The mass number of the atom of an element is the sum of the number of protons and neutrons in the atom. (True / False)

Explanation

To determine whether the statement "The mass number of the atom of an element is the sum of the number of protons and neutrons in the atom" is true or false, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Mass Number**:
- The mass number (A) of an atom is defined as the total number of protons and neutrons present in the nucleus of that atom.

2. **Identifying Protons and Neutrons**:
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