Select the correct alternative from the choices given :
Which, among the following polymers, is a polyester?

Options

A. Melamine
B. Bakelite
C. Terylene
D. Polythene

Explanation

To determine which polymer among the given options is a polyester, we need to understand what a polyester is and identify its characteristics.

### Step-by-Step Solution:

1. **Definition of Polyester**:
- A polyester is a type of polymer that contains ester functional groups in its main chain. The term "polyester" indicates that it is made up of multiple ester units.

2. **Identifying Ester Functional Group**:
- The ester functional group has the general structure -COO-. In polyesters, these ester groups are formed through the reaction of a diacid and a diol.

3. **Examples of Polyesters**:
- Common examples of polyesters include Terylene (also known as Dacron) and Glyptal. Terylene is made from the monomers terephthalic acid and ethylene glycol.

4. **Chemical Reaction**:
- The formation of Terylene involves a condensation reaction between terephthalic acid and ethylene glycol. During this reaction, water (H2O) is eliminated, and ester bonds are formed.
- The reaction can be summarized as:
- Terephthalic acid (C6H4(COOH)2) + Ethylene glycol (HO-CH2-CH2-OH) → Terylene + H2O

5. **Structure of Terylene**:
- The repeating unit of Terylene includes the ester linkage (-COO-) connecting the terephthalic acid and ethylene glycol units.

6. **Conclusion**:
- Based on the definition and examples, the correct alternative among the given choices that represents a polyester is Terylene.

### Final Answer:
The correct alternative that represents a polyester is **Terylene**.

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