Which of the following statement is not correct about carbon dioxide acting as a fire extinguisher for electrical fires ?

Options

A. it is heavier than air
B. it is lighter than air
C. it is not combustible
D. it does not support combustion

Answer

To determine which statement is not correct about carbon dioxide acting as a fire extinguisher for electrical fires, we need to analyze the provided options based on the properties of carbon dioxide.

### Step-by-Step Solution:

1. **Understanding Carbon Dioxide**:
- Carbon dioxide (CO2) is a gas that is commonly used in fire extinguishers, especially for electrical fires. It works by displacing oxygen, which is necessary for combustion.

2. **Analyzing the Statements**:
- We need to evaluate each statement given in the options to find the one that is incorrect.

3. **Option 1: "Carbon dioxide is heavier than air."**
- This statement is **correct**. Carbon dioxide is indeed heavier than air, which allows it to settle over the fire and suffocate it.

4. **Option 2: "Carbon dioxide is lighter than air."**
- This statement is **incorrect**. As mentioned, carbon dioxide is heavier than air, so this option is the one we are looking for.

5. **Option 3: "Carbon dioxide is not combustible."**
- This statement is **correct**. Carbon dioxide does not burn and is not a combustible substance.

6. **Option 4: "Carbon dioxide does not support combustion."**
- This statement is also **correct**. Carbon dioxide acts as a blanket over the fire, cutting off the oxygen supply necessary for combustion.

7. **Conclusion**:
- The statement that is not correct about carbon dioxide acting as a fire extinguisher for electrical fires is **Option 2: "Carbon dioxide is lighter than air."**

### Final Answer:
The statement that is not correct is: **"Carbon dioxide is lighter than air."**

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