Heavy water is used as a

Options

A. fuel in engines
B. semiconductor
C. moderator in nuclear reactors
D. insulator in steam engines.

Answer

**Step-by-Step Solution:**

1. **Understanding Heavy Water**: Heavy water is chemically represented as D₂O, where D stands for deuterium, an isotope of hydrogen. In contrast, regular water is represented as H₂O, which contains the common hydrogen isotope.

2. **Preparation of Heavy Water**: Heavy water is produced through the process of electrolysis of ordinary water (H₂O) in the presence of a small amount of alkali. This process allows for the separation of deuterium from regular hydrogen.

3. **Uses of Heavy Water**: The primary use of heavy water is in nuclear reactors. It serves as a neutron moderator, which means it slows down neutrons produced during nuclear fission.

4. **Function of Heavy Water in Nuclear Reactors**: In a nuclear reactor, heavy water (D₂O) slows down neutrons, making them more likely to interact with fissile materials like uranium-235. This is crucial because uranium-235 is the isotope that undergoes fission, releasing energy.

5. **Importance of Neutron Moderation**: The moderation of neutrons is essential in sustaining a controlled nuclear chain reaction. Heavy water is particularly effective because it can slow down neutrons without capturing them, allowing for a higher probability of fission with uranium-235 compared to uranium-238, which tends to capture neutrons without fissioning.

6. **Conclusion**: Therefore, the correct answer to the question "Heavy water is used as a" is that it is used as a **moderator in nuclear reactors**.

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