........... is a non-electrolyte.

Options

A. Acetic acid
B. Sugar
C. Calcium
D. Potassium

Explanation

**Step-by-Step Solution:**

1. **Understanding Non-Electrolytes**: A non-electrolyte is a substance that does not dissociate into ions when dissolved in water. This means it does not conduct electricity in an aqueous solution.

2. **Identifying Examples**: Common examples of non-electrolytes include substances like sugar (sucrose, C12H22O11) and alcohols. These substances remain intact and do not break down into ions.

3. **Differentiating Electrolytes and Non-Electrolytes**: Electrolytes are substances that dissociate into ions in solution, allowing them to conduct electricity. For example, acetic acid is a weak electrolyte because it partially dissociates into ions.

4. **Analyzing Specific Substances**:
- **Acetic Acid**: Dissociates into ions in aqueous solution, making it an electrolyte.
- **Sugar (Sucrose)**: Does not dissociate into ions in aqueous solution, making it a non-electrolyte.
- **Calcium and Potassium**: These metals can conduct electricity when in molten form or when they dissociate into ions, thus they are classified as electrolytes.

5. **Conclusion**: Based on the analysis, the correct answer to the question "........... is a non-electrolyte" is **sugar (sucrose)**.

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