Each of the following oxide dissolves in water to give an aqueous solution which turns red litmus blue except

Options

A. MgO
B. CaO
C. `CO_(2)`
D. `Na_(2)O`

Explanation

To solve the question, we need to identify which oxide does not turn red litmus paper blue when dissolved in water. Here’s a step-by-step solution:

### Step 1: Understand the properties of oxides
Oxides can be classified into two main categories: basic oxides and acidic oxides. Basic oxides are typically formed from metals and will turn red litmus paper blue when dissolved in water, indicating a basic solution. Acidic oxides are usually formed from non-metals and will not change the color of red litmus paper.

### Step 2: Identify the oxides in question
We need to analyze the given oxides. Common examples include:
- Magnesium Oxide (MgO)
- Calcium Oxide (CaO)
- Carbon Dioxide (CO2)
- Sodium Oxide (Na2O)

### Step 3: Analyze each oxide
1. **Magnesium Oxide (MgO)**: This is a metal oxide. When dissolved in water, it forms magnesium hydroxide, which is basic. Therefore, it will turn red litmus paper blue.

2. **Calcium Oxide (CaO)**: This is also a metal oxide. When dissolved in water, it forms calcium hydroxide, which is basic. Thus, it will turn red litmus paper blue.

3. **Carbon Dioxide (CO2)**: This is a non-metal oxide. When dissolved in water, it forms carbonic acid (H2CO3), which is acidic. Therefore, it will not turn red litmus paper blue; instead, it will keep the red litmus paper red.

4. **Sodium Oxide (Na2O)**: This is a metal oxide. When dissolved in water, it forms sodium hydroxide, which is basic. Thus, it will turn red litmus paper blue.

### Step 4: Conclusion
From the analysis, the oxide that does not turn red litmus paper blue is **Carbon Dioxide (CO2)**, as it forms an acidic solution when dissolved in water.

### Final Answer
The oxide that does not turn red litmus blue is **Carbon Dioxide (CO2)**.

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