Heavy water is obtained by

Options

A. boiling water
B. heating `H_(2)O_(2)`
C. prolonged electrolysis of `H_(2)O`
D. all of these.

Explanation

**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, ordinary water is represented as H2O.

2. **Source of Heavy Water**: Ordinary water (H2O) contains a very small fraction of heavy water (D2O). This means that D2O is present in trace amounts in regular water.

3. **Electrolysis Process**: When we perform electrolysis on ordinary water (H2O), it breaks down into hydrogen gas (H2) and oxygen gas (O2). The reaction can be summarized as:
\[ 2H_2O \rightarrow 2H_2 + O_2 \]

4. **Behavior of Heavy Water**: During the electrolysis of water, D2O does not electrolyze in the same manner as H2O. This means that while H2O is broken down into gases, D2O remains in the solution.

5. **Prolonged Electrolysis**: By conducting repeated or prolonged electrolysis of H2O, the lighter hydrogen (H2) is gradually removed, leaving behind a higher concentration of D2O. This is because the D2O does not get converted into gas as readily as H2O does.

6. **Conclusion**: Therefore, heavy water (D2O) is obtained through the process of prolonged electrolysis of ordinary water (H2O).

**Final Answer**: Heavy water is obtained by prolonged electrolysis of H2O.

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