Which of the following halogen oxide is used for estimation of carbon monoxide in automobile exhaust gases?

Options

A. `Cl_2O_7`
B. `I_2O_5`
C. `ClO_2`
D. `BrO_3`

Answer

To solve the question regarding which halogen oxide is used for the estimation of carbon monoxide in automobile exhaust gases, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Halogen Oxides**:
The question asks about halogen oxides. Common halogen oxides include I2O5 (iodine pentoxide), Cl2O (dichlorine monoxide), BrO (bromine monoxide), and others.

2. **Understand the Reaction with Carbon Monoxide**:
We need to find out which halogen oxide can react with carbon monoxide (CO) to produce a measurable product.

3. **Research the Reaction of I2O5 with CO**:
The reaction of carbon monoxide with iodine pentoxide (I2O5) is as follows:
\[ 2 \text{CO} + \text{I}_2\text{O}_5 \rightarrow 5 \text{CO}_2 + \text{I}_2 \]
This reaction shows that I2O5 reacts with CO to produce carbon dioxide (CO2) and iodine (I2).

4. **Confirm the Use of I2O5 for Estimation**:
The iodine produced can be further reacted with sodium thiosulfate (Na2S2O3) for quantitative analysis. This makes I2O5 suitable for estimating the amount of carbon monoxide present.

5. **Select the Correct Option**:
Based on the reaction and its application, we conclude that I2O5 is the halogen oxide used for the estimation of carbon monoxide in automobile exhaust gases.

Thus, the correct answer is **Option B: I2O5**.