Which of the following oxides in aqueous solution does not turn red litmus blue?

Options

A. `CO_2`
B. `Na_2 O`
C. `MgO`
D. `Fe_2 O_3`

Explanation

To solve the question "Which of the following oxides in aqueous solution does not turn red litmus blue?", we can follow these steps:

### Step 1: Understand the Nature of Oxides
Oxides can be classified into two categories based on the elements they are derived from: metallic oxides and non-metallic oxides.

- **Metallic Oxides**: These are formed when metals combine with oxygen. They are generally basic in nature.
- **Non-Metallic Oxides**: These are formed when non-metals combine with oxygen. They are generally acidic in nature.

### Step 2: Identify the Effect on Litmus Paper
Litmus paper is used to test the acidity or basicity of a solution:
- **Red Litmus Paper**: Turns blue in basic solutions.
- **Red Litmus Paper**: Remains red in acidic solutions.

### Step 3: Determine the Nature of Each Oxide
Given the options (let's assume they are sodium oxide, magnesium oxide, iron oxide, and carbon dioxide), we can categorize them:
- **Sodium Oxide (Na2O)**: Metallic oxide, basic.
- **Magnesium Oxide (MgO)**: Metallic oxide, basic.
- **Iron Oxide (Fe2O3)**: Metallic oxide, basic.
- **Carbon Dioxide (CO2)**: Non-metallic oxide, acidic.

### Step 4: Conclusion
Since we are looking for the oxide that does not turn red litmus blue, we need to identify the acidic oxide. In this case, carbon dioxide (CO2) is the only non-metallic oxide listed, which is acidic and will not turn red litmus blue.

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

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