When magnesium is burned in air, a powdery ash X is formed. X on dissolving in water forms Y.
What is the action of Y on litmus paper ?

Answer

To solve the question step by step, we will break down the process of what happens when magnesium is burned in air and how it interacts with water and litmus paper.

### Step-by-Step Solution:

1. **Identify the Reaction**:
When magnesium (Mg) is burned in air (which contains oxygen), it reacts with oxygen to form magnesium oxide (MgO).
- **Equation**:
\[ 2Mg + O_2 \rightarrow 2MgO \]
- Here, the powdery ash formed is identified as **X**, which is magnesium oxide (MgO).

2. **Dissolving in Water**:
When magnesium oxide (X) is dissolved in water, it forms magnesium hydroxide (Y).
- **Equation**:
\[ MgO + H_2O \rightarrow Mg(OH)_2 \]
- Here, **Y** is magnesium hydroxide (Mg(OH)₂).

3. **Determine the Nature of Y**:
Magnesium hydroxide (Y) is a basic compound. Basic substances typically have a pH greater than 7.

4. **Action of Y on Litmus Paper**:
Litmus paper is used to test the acidity or basicity of a solution.
- If a solution is basic, it will turn red litmus paper blue.
- Since magnesium hydroxide is basic, it will turn red litmus paper blue.

5. **Conclusion**:
The action of Y (magnesium hydroxide) on litmus paper is that it changes red litmus paper to blue.

### Final Answer:
The action of Y (magnesium hydroxide) on litmus paper is that it turns red litmus paper blue.

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