Which isotope of carbon is used for getting relative atomic masses?

Explanation

**Step-by-Step Solution:**

1. **Identify the Isotopes of Carbon**: Carbon has several isotopes, the most common being Carbon-12 (C-12) and Carbon-13 (C-13).

2. **Understand the Concept of Relative Atomic Mass**: Relative atomic mass is a weighted average of the masses of an element's isotopes, taking into account their natural abundance.

3. **Determine the Reference Isotope**: The standard reference isotope for calculating relative atomic masses is Carbon-12 (C-12).

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