What is heavy water?

Options

A. `H_(2)^(18)O`
B. `H_(2)^(16)O`
C. `H_(2)O_(3)`
D. `D_(2)O`

Answer

**Step-by-Step Solution:**

1. **Definition of Heavy Water**: Heavy water is a form of water that contains a higher proportion of the hydrogen isotope deuterium (D) instead of the more common hydrogen isotope protium (H).

2. **Understanding Isotopes**: Isotopes are variants of a particular chemical element that have the same number of protons (atomic number) but different numbers of neutrons, resulting in different mass numbers. For hydrogen, there are three isotopes:
- Protium (¹H or H) with 1 proton and 0 neutrons.
- Deuterium (²H or D) with 1 proton and 1 neutron.
- Tritium (³H or T) with 1 proton and 2 neutrons.

3. **Composition of Heavy Water**: In heavy water, the hydrogen atoms are primarily deuterium. Therefore, the chemical formula for heavy water is D₂O, where D represents deuterium and O represents oxygen.

4. **Oxygen Isotopes**: While discussing heavy water, it's also important to note that oxygen has isotopes, primarily oxygen-16 (¹⁶O) and oxygen-18 (¹⁸O). However, in heavy water, the oxygen isotope present is typically oxygen-16.

5. **Conclusion**: The formula for heavy water is D₂O, indicating that it consists of two deuterium atoms and one oxygen atom.

**Final Answer**: Heavy water is represented by the chemical formula D₂O.

---