List some important uses of isotopes.

Explanation

### Step-by-Step Text Solution:

1. **Definition of Isotopes**:
- Isotopes are variants of a chemical element that have the same number of protons (atomic number) but different numbers of neutrons, resulting in different mass numbers. For example, Carbon-12 (C-12) and Carbon-14 (C-14) are isotopes of carbon.

2. **Use of Carbon-14 (C-14)**:
- C-14 is widely used in carbon dating, a method that helps determine the age of ancient organic materials, such as fossils. This technique measures the amount of C-14 remaining in a sample to estimate how long it has been since the organism died.

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