Green chemistry has helped in developed of process for manufacture of polystyrene foam sheet packaging material by using `…………….` as the blowing agent.

Options

A. steam
B. `CO_(2)`
C. `CFCs`
D. methane.

Answer

To solve the question regarding the blowing agent used in the manufacture of polystyrene foam sheet packaging material through green chemistry, we will analyze the options provided and determine which one aligns with the principles of green chemistry.

### Step-by-Step Solution:

1. **Understanding Green Chemistry**:
- Green chemistry focuses on creating processes that are environmentally friendly and reduce the use of toxic substances. It emphasizes the use of safer alternatives to harmful chemicals.

**Hint**: Remember that green chemistry aims to minimize environmental impact.

2. **Evaluating the Options**:
- The options given are steam, CO2, CFC, and methane. We need to analyze each option in the context of their environmental impact and suitability as a blowing agent.

3. **Analyzing Steam**:
- Steam is a form of water vapor and is considered a greenhouse gas. It can contribute to global warming by trapping heat in the atmosphere. Therefore, using steam as a blowing agent is not ideal.

**Hint**: Consider the greenhouse effect when evaluating steam.

4. **Analyzing CO2**:
- Carbon dioxide (CO2) can be captured as a byproduct from various industrial processes. It is less harmful compared to other options and can be utilized effectively in the production of polystyrene foam. This aligns with the principles of green chemistry.

**Hint**: Think about the sources of CO2 and its potential for reuse in industrial applications.

5. **Analyzing CFC**:
- Chlorofluorocarbons (CFCs) are known to deplete the ozone layer and are considered highly toxic. Their use is strictly regulated and avoided in green chemistry practices.

**Hint**: Remember that substances harmful to the ozone layer are not suitable for green chemistry.

6. **Analyzing Methane**:
- Methane (CH4) is another greenhouse gas that contributes to climate change. Its use as a blowing agent would contradict the goals of green chemistry.

**Hint**: Consider the environmental impact of methane when evaluating its use.

7. **Conclusion**:
- After evaluating all options, CO2 emerges as the most suitable blowing agent for the manufacture of polystyrene foam sheet packaging material in accordance with green chemistry principles.

### Final Answer:
**CO2** is used as the blowing agent in the manufacture of polystyrene foam sheet packaging material through green chemistry.