The pair of thermosetting plastic is

Question

Accepted Answer

The correct answer is Option 4: Bakelite, Melamine. Let's explore why this is the correct choice and why the other options are incorrect.

1. **Explanation for Option 4 (Bakelite, Melamine):**
   - **Bakelite**: This is a well-known thermosetting plastic. It is formed by the condensation reaction of phenol and formaldehyde. Once set, Bakelite cannot be remolded or reheated into a new shape. It is known for its excellent electrical insulating properties and heat resistance, making it ideal for electrical switches, handles, and other applications.
   - **Melamine**: This is another thermosetting plastic. It is often used in the production of laminates, dinnerware, and flame-resistant fabrics. Melamine is known for its hardness, resistance to heat, and ability to retain its shape once set.

Both Bakelite and Melamine are thermosetting plastics, meaning they undergo a chemical change when heated and molded, and cannot be remolded or reheated after the initial forming process.

2. **Explanation for why other options are incorrect:**

- **Option 1 (Polythene, PVC):**
     - **Polythene (Polyethylene)**: This is a thermoplastic, not a thermosetting plastic. It can be melted and reshaped multiple times.
     - **PVC (Polyvinyl Chloride)**: Although PVC can be made into a rigid form, it is still a thermoplastic. It can be softened by heating and reshaped, which is a characteristic of thermoplastics, not thermosetting plastics.

- **Option 2 (Polythene, Melamine):**
     - **Polythene**: As mentioned, this is a thermoplastic and not a thermosetting plastic.
     - **Melamine**: While Melamine is a thermosetting plastic, the presence of Polythene in this option makes it incorrect.

- **Option 3 (Bakelite, PVC):**
     - **Bakelite**: This is correctly identified as a thermosetting plastic.
     - **PVC**: As previously explained, PVC is a thermoplastic, not a thermosetting plastic. This makes the pair incorrect.

In conclusion, Option 4 is the only pair where both materials, Bakelite and Melamine, are thermosetting plastics. This is why it is the correct answer.