Milk of magnesia is an

Options

A. acid
B. ant acid
C. alkali
D. rock salt

Explanation

**Step-by-Step Solution:**

1. **Understanding Milk of Magnesia**:
- Milk of Magnesia is a common name for Magnesium Hydroxide, which has the chemical formula \( \text{Mg(OH)}_2 \).

2. **Identifying its Nature**:
- To determine whether Milk of Magnesia is an acid, base, or salt, we need to analyze its behavior in water.

3. **Dissolution in Water**:
- When Milk of Magnesia is dissolved in water, it dissociates to release hydroxide ions (\( \text{OH}^- \)). This can be represented as:
\[ \text{Mg(OH)}_2 \rightarrow \text{Mg}^{2+} + 2\text{OH}^- \]

4. **Effect on pH**:
- The release of hydroxide ions increases the concentration of \( \text{OH}^- \) in the solution. This increase in \( \text{OH}^- \) ions leads to a rise in the pH of the solution.

5. **Conclusion**:
- Since an increase in pH indicates that the solution is basic, we conclude that Milk of Magnesia is classified as a base. More specifically, it is an alkali because it dissolves in water to produce hydroxide ions.

**Final Answer**: Milk of Magnesia is an **alkali**.

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