Milk of magnesia is :-

Options

A. Suspension of `Mg(OH)_(2)` in water
B. Colloid of `Mg(OH)_(2)` in water
C. True solution of `Mg(OH)_(2)` in water
D. Pure `Mg(OH)_(2)`

Answer

**Step-by-Step Solution:**

1. **Identify the Substance**: The question asks about "milk of magnesia". We need to determine what this substance is and its composition.

2. **Understand its Composition**: Milk of magnesia is primarily composed of magnesium hydroxide. It is important to note that it is not just magnesium or any other compound.

3. **Define the Form**: Milk of magnesia is not a solid or a true solution; it is classified as a suspension. A suspension is a heterogeneous mixture where the particles are larger than those found in a true solution.

4. **Explain its Use**: Milk of magnesia is commonly used as an antacid. It helps neutralize stomach acid and relieve symptoms of indigestion.

5. **Summarize the Characteristics**: To summarize, milk of magnesia is a suspension of magnesium hydroxide in water, used primarily for its antacid properties.

6. **Final Answer**: Therefore, the correct answer to the question is that milk of magnesia is a suspension of magnesium hydroxide in water.

---