Which among the following is not a green house gas?

Options

A. Carbon dioxide
B. Oxygen
C. Methane
D. Chlorofluorocarbons

Explanation

To determine which among the given options is not a greenhouse gas, we can follow these steps:

### Step 1: Understand what greenhouse gases are
Greenhouse gases are gases that trap heat in the atmosphere and contribute to the greenhouse effect. Common greenhouse gases include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ozone (O3), and chlorofluorocarbons (CFCs).

### Step 2: Analyze the options provided
The options given are:
1. Carbon dioxide (CO2)
2. Oxygen (O2)
3. Methane (CH4)
4. Chlorofluorocarbon (CFCs)

### Step 3: Identify which gases are greenhouse gases
- **Carbon dioxide (CO2)**: This is a well-known greenhouse gas.
- **Methane (CH4)**: This is also a significant greenhouse gas.
- **Chlorofluorocarbon (CFCs)**: These are synthetic compounds that also act as greenhouse gases.
- **Oxygen (O2)**: This gas is essential for life but does not contribute to the greenhouse effect.

### Step 4: Conclude which is not a greenhouse gas
From the analysis, it is clear that oxygen (O2) is not a greenhouse gas, while the other three options are.

### Final Answer:
**Oxygen (O2) is not a greenhouse gas.**

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