Which one of the following substances used a dry cleaning is a better strategy to control environmental pollution

Options

A. Sulphur dioxide
B. Carbon dioxide
C. Nitrogen doxide
D. Tetrachloroethylene

Explanation

To determine which substance used in dry cleaning is a better strategy to control environmental pollution, we need to analyze the options provided: Sulphur dioxide (SO2), Carbon dioxide (CO2), Nitrogen dioxide (NO2), and Tetrachloroethylene (C2Cl4).

### Step 1: Identify the substances and their uses
- **Sulphur Dioxide (SO2)**: Primarily produced from burning fossil fuels and can contribute to air pollution and acid rain.
- **Carbon Dioxide (CO2)**: A greenhouse gas produced from various human activities, including burning fossil fuels, but not used in dry cleaning.
- **Nitrogen Dioxide (NO2)**: A pollutant from vehicle emissions and industrial processes, not used in dry cleaning.
- **Tetrachloroethylene (C2Cl4)**: A solvent commonly used in dry cleaning processes.

### Step 2: Analyze the environmental impact of each substance
- **SO2**: Contributes to air pollution and acid rain, harmful to the environment.
- **CO2**: While it is a significant greenhouse gas, it is not a dry cleaning solvent.
- **NO2**: Contributes to smog and respiratory problems, not used in dry cleaning.
- **C2Cl4**: While it is effective in cleaning, it is also a volatile organic compound (VOC) that can contribute to air pollution.

### Step 3: Determine the best option for controlling pollution
Among the listed substances, **Tetrachloroethylene (C2Cl4)** is the only one used in dry cleaning. However, it has environmental concerns due to its VOC nature. The other options (SO2, CO2, NO2) are not suitable for dry cleaning and have significant negative environmental impacts.

### Conclusion
While Tetrachloroethylene is used in dry cleaning, it is essential to consider its environmental effects. However, since it is the only substance listed that is used for dry cleaning, it is the correct answer to the question.

**Final Answer: Tetrachloroethylene (C2Cl4)**

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