**Correct Option: A. Polyethylene** ### Detailed Explanation **1. Understanding Addition Polymerization:** Addition polymerization is a type of polymerization where monomers (small molecules) join together to form a polymer (a large molecule) without the loss of any small molecules. This process typically involves unsaturated monomers that contain double bonds (C=C). When these double bonds open up, they allow the monomers to link together, forming long chains. **2. Analyzing the Options:** - **A. Polyethylene:** - Polyethylene is a synthetic polymer made from the polymerization of ethylene (ethylene is the monomer with the formula C2H4). The reaction involves the breaking of the double bond in ethylene, allowing the monomers to connect in a long chain. This process is a classic example of addition polymerization. - **B. Nylon:** - Nylon is a type of polyamide, which is produced through a different process called condensation polymerization. In this process, monomers with two functional groups (like amines and carboxylic acids) react to form a polymer while releasing small molecules, such as water. Therefore, nylon does not fit the criteria for addition polymerization. - **C. Polystyrene:** - Polystyrene is indeed produced through addition polymerization, as it is made from the monomer styrene (C8H8). However, while polystyrene is a correct answer in the context of addition polymerization, the question asks for the polymer that is "primarily" produced through this process. Polyethylene is more commonly associated with addition polymerization in educational contexts. - **D. Polyurethane:** - Polyurethane is produced through a reaction between diisocyanates and polyols, which is also a form of condensation polymerization. This process involves the formation of urethane linkages and typically releases small molecules, making it unsuitable for addition polymerization. ### Why the Other Options are Weaker: - **B. Nylon:** Incorrect because it is formed through condensation polymerization, not addition polymerization. - **C. Polystyrene:** While it is produced through addition polymerization, it is not as widely recognized as the primary example of this process compared to polyethylene. - **D. Polyurethane:** Incorrect as it is formed through a different mechanism (condensation polymerization) and involves the release of small molecules. ### Summary of Key Concepts: - **Addition Polymerization:** Involves the joining of unsaturated monomers without the loss of small molecules. - **Polyethylene:** A prime example of a polymer produced through addition polymerization from ethylene. - **Condensation Polymerization:** Involves the formation of polymers with the release of small molecules; examples include nylon and polyurethane. - **Polystyrene:** Also produced through addition polymerization but less commonly highlighted than polyethylene. ### Revision Summary: - Addition polymerization involves the linking of monomers with double bonds. - Polyethylene is the most recognized polymer produced through this process. - Nylon and polyurethane are produced through condensation polymerization. - Polystyrene is also an addition polymer but is secondary to polyethylene in educational contexts.