Which of the following are thermoplastic polymers?
(i) Polyvinyl chloride
(ii) Bakelite
(iii) Teflon
(iv) Melamine

Options

A. (i) and (ii)
B. (i) and (iv)
C. (i) and (iii)
D. All of these

Explanation

To determine which of the given options are thermoplastic polymers, we need to understand the characteristics of thermoplastic and thermosetting polymers.

**Step 1: Understand Thermoplastic Polymers**
- Thermoplastic polymers are materials that become soft when heated and harden upon cooling. They can be reshaped and remolded multiple times without undergoing any significant chemical change.

**Step 2: Analyze Each Option**
- (i) **Polyvinyl chloride (PVC)**: This is a thermoplastic polymer. It can be softened upon heating and reshaped.
- (ii) **Bakelite**: This is a thermosetting polymer. Once it is set, it cannot be remolded or reshaped.
- (iii) **Teflon (PTFE)**: This is a thermoplastic polymer. It can also be softened upon heating and reshaped.
- (iv) **Melamine**: This is a thermosetting polymer. Like Bakelite, it cannot be reshaped once it has set.

**Step 3: Conclusion**
- The thermoplastic polymers from the given options are:
- (i) Polyvinyl chloride (PVC)
- (iii) Teflon (PTFE)

**Final Answer:**
The thermoplastic polymers among the options are (i) Polyvinyl chloride and (iii) Teflon.

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