The correct option is **C. Polyethylene Terephthalate (PET)**. ### Detailed Explanation: 1. **Understanding Synthetic Polymers**: Synthetic polymers are large molecules made up of repeating structural units (monomers) that are chemically bonded together. They are widely used in various applications, including packaging, textiles, and construction materials. Each type of polymer has unique properties that make it suitable for specific uses. 2. **Properties of PET**: - **Barrier Properties**: PET is known for its excellent barrier properties, which means it effectively prevents the passage of gases and moisture. This is crucial for packaging food and beverages, as it helps maintain freshness and prevents spoilage. - **Durability**: PET is strong and resistant to impact, making it ideal for containers that need to withstand handling and transportation. - **Recyclability**: PET is one of the most recycled plastics globally, which adds to its appeal in sustainable packaging solutions. 3. **Applications of PET**: PET is primarily used in the production of plastic bottles (like those for soft drinks and water) and containers for food products. Its combination of strength, clarity, and barrier properties makes it the preferred choice for these applications. ### Why the Other Options Are Incorrect: - **A. Polyethylene (PE)**: - **Properties**: While polyethylene is widely used in packaging, it does not have the same level of barrier properties as PET. It is more permeable to gases and moisture, which can lead to quicker spoilage of contents. - **Applications**: PE is commonly used for bags, films, and containers, but it is not the primary choice for bottles that require excellent barrier properties. - **B. Polyvinyl Chloride (PVC)**: - **Properties**: PVC is a versatile plastic but is less commonly used for food and beverage containers due to concerns about leaching chemicals and its rigidity compared to PET. - **Applications**: PVC is more often used in construction materials, plumbing, and electrical cable insulation rather than in food packaging. - **D. Polystyrene (PS)**: - **Properties**: Polystyrene is known for being lightweight and having good insulation properties, but it is brittle and not suitable for applications requiring durability and barrier properties. - **Applications**: PS is often used for disposable cutlery, foam packaging, and insulation, but it is not used for bottles or containers that need to maintain the integrity of their contents. ### Summary of Key Points: - **Correct Answer**: C. Polyethylene Terephthalate (PET) is primarily used for plastic bottles and containers due to its excellent barrier properties and durability. - **PET Properties**: Strong, durable, excellent barrier against gases and moisture, and highly recyclable. - **Other Options**: PE is less effective for barrier applications, PVC is not ideal for food packaging, and PS is brittle and not suitable for containers. - **Applications**: PET is the preferred choice for packaging beverages and food products, ensuring freshness and safety. This thorough understanding of the properties and applications of different synthetic polymers will help you in your studies and exams related to chemistry and materials science.