Which of the following gas causes green house effect to maximum extent?

Options

A. `CH_4`
B. Water vapour
C. `N_2O` `CO_2`
D. `CO_2`

Answer

To determine which gas causes the greenhouse effect to the maximum extent, we can analyze the options provided: methane (CH4), water vapor (H2O), nitrogen (N2), and carbon dioxide (CO2).

### Step-by-Step Solution:

1. **Understanding Greenhouse Gases**:
- Greenhouse gases are substances that trap heat in the atmosphere. They allow sunlight to enter the atmosphere but prevent some of the heat that the Earth radiates back into space from escaping.

2. **List of Gases**:
- The gases mentioned are:
- Methane (CH4)
- Water vapor (H2O)
- Nitrogen (N2)
- Carbon dioxide (CO2)

3. **Analyzing Each Gas**:
- **Methane (CH4)**:
- Methane is a potent greenhouse gas, but it is present in smaller quantities compared to CO2. It has a higher global warming potential over a short time frame but is less abundant.
- **Water Vapor (H2O)**:
- Water vapor is the most abundant greenhouse gas and plays a significant role in the greenhouse effect. However, it is considered a feedback mechanism rather than a direct forcing agent since its concentration is largely controlled by temperature.
- **Nitrogen (N2)**:
- Nitrogen is not a greenhouse gas. It does not trap heat and makes up a large portion of the atmosphere but does not contribute to the greenhouse effect.
- **Carbon Dioxide (CO2)**:
- CO2 is a significant greenhouse gas due to its ability to trap heat and its increasing concentration in the atmosphere due to human activities like burning fossil fuels.

4. **Conclusion**:
- While water vapor is abundant and has a strong effect, CO2 is the primary greenhouse gas responsible for long-term climate change due to its increasing levels and its role in trapping heat. Therefore, among the options, **carbon dioxide (CO2)** causes the greenhouse effect to the maximum extent.

### Final Answer:
**Carbon Dioxide (CO2)** causes the greenhouse effect to the maximum extent.

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