Which of the following gas is used in warfare

Options

A. `N_(2)O`
B. `C Cl_(3).NO_(2)`
C. `CO_(2)`
D. `O_(2)`

Explanation

To determine which gas is used in warfare from the given options, let's analyze each option step by step:

### Step 1: Identify the gases listed in the options
The options provided are:
1. N2 (Nitrogen gas)
2. CCl3 or NO2 (Chloropicrine or Nitrogen dioxide)
3. CO2 (Carbon dioxide)
4. O2 (Oxygen)

### Step 2: Analyze each gas for its use in warfare
1. **N2 (Nitrogen gas)**:
- Nitrogen is a non-toxic gas that makes up about 78% of the Earth's atmosphere. It is not used in warfare.

2. **CCl3 or NO2 (Chloropicrine or Nitrogen dioxide)**:
- Chloropicrine (CCl3) is a chemical compound that has been used as a chemical weapon in warfare, particularly in World War I. It is a toxic gas that can cause severe respiratory issues and is classified as a chemical warfare agent.
- Nitrogen dioxide (NO2) is also a toxic gas but is not primarily known for its use in warfare compared to Chloropicrine.

3. **CO2 (Carbon dioxide)**:
- Carbon dioxide is a naturally occurring gas that is not toxic at normal atmospheric levels. It is not used in warfare.

4. **O2 (Oxygen)**:
- Oxygen is essential for life and is not used as a weapon in warfare.

### Step 3: Conclusion
Based on the analysis, the gas that is used in warfare from the options provided is **CCl3 (Chloropicrine)**.

### Final Answer:
The gas used in warfare is **CCl3 (Chloropicrine)**.

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