Gas X is the major component of air. Among the following identify the true statement regarding X.

Options

A. X is used as a fire extinguisher.
B. X is essential for rusting.
C. X is highly soluble in water.
D. X is a very unreactive gas.

Explanation

To solve the question regarding gas X, which is the major component of air, we will analyze the options provided and identify the true statement about gas X.

### Step-by-Step Solution:

1. **Identify the Major Component of Air**:
- Air is a mixture of various gases. The major components of air are nitrogen (N2), oxygen (O2), carbon dioxide (CO2), and trace gases.
- Nitrogen makes up about 78% of air, while oxygen constitutes about 21%. The remaining gases are present in very small amounts.

2. **Analyze the Options**:
- We need to evaluate the statements provided regarding gas X (which we identified as nitrogen).

3. **Evaluate Each Statement**:
- **Option 1**: "Gas X is used as a fire extinguisher."
- This statement is false. Carbon dioxide (CO2) is commonly used in fire extinguishers, not nitrogen.

- **Option 2**: "Gas X is essential for rusting."
- This statement is also false. Rusting is primarily caused by the presence of oxygen (O2), not nitrogen.

- **Option 3**: "Gas X is highly soluble in water."
- This statement is false. Carbon dioxide is the gas that is highly soluble in water, while nitrogen is not.

- **Option 4**: "Gas X is a very unreactive gas."
- This statement is true. Nitrogen (N2) is known to be an unreactive gas due to its strong triple bond (N≡N), which makes it stable and less likely to react with other substances.

4. **Conclusion**:
- The true statement regarding gas X (which is nitrogen) is that it is a very unreactive gas. Therefore, the correct answer is **Option 4**.