Polyethylene terephthalate, commonly abbreviated as PET, is a very familiar form of which type of synthetic polymer that is widely used for making plastic bottles and food containers?

Introduction / Context:
This general knowledge chemistry question asks about the nature of PET, which most people encounter in the form of soft drink bottles, food packaging and synthetic fibres. Knowing what type of polymer PET is helps connect everyday materials with fundamental concepts in organic and polymer chemistry, especially the classification of plastics such as polyesters, polyamides and others.

Given Data / Assumptions:

• The polymer in question is PET, which stands for polyethylene terephthalate.
• PET is widely used for making bottles and many transparent plastic containers.
• We need to identify the broad class of synthetic material (for example, nylon, acrylic, polyester or rayon) to which PET belongs.
• We assume introductory level knowledge about different families of polymers.

Concept / Approach:
PET is formed by the condensation polymerisation of ethylene glycol with terephthalic acid or dimethyl terephthalate. The repeating units are linked by ester bonds (–COO–) formed between carboxylic acid and alcohol groups. A polymer whose backbone contains such ester linkages in the main chain is called a polyester. PET can be spun into fibres, used as a film and moulded into bottles, making it one of the best known polyester materials in daily life.

Step-by-Step Solution:
1) Recall that PET stands for polyethylene terephthalate, an important synthetic polymer.2) Identify the functional group linking the repeating units: an ester group formed by reaction of an acid and an alcohol.3) Polymers that have ester linkages (–COO–) in the main chain are classified broadly as polyesters.4) Nylon, on the other hand, has amide linkages (–CONH–) and belongs to the polyamide family.5) Acrylic materials are usually based on derivatives of acrylic or methacrylic acid, such as polymethyl methacrylate (PMMA), and do not specifically match PET structure.6) Rayon is regenerated cellulose obtained from natural cellulose and is not the same as PET, even though both can be used as fibres.7) Therefore, the correct classification of PET is that it is a polyester.

Verification / Alternative check:
In textbooks and packaging codes, PET is grouped under polyesters. Its recycling symbol often shows the number 1 with the word PET, indicating the material class. Clothing labels may mention polyester fibres, some of which are made from PET. Industrial literature also describes PET as a thermoplastic polyester used for fibres, films and bottles. These references confirm that polyester is the correct category, not nylon, acrylic, polyethylene or rayon.

Why Other Options Are Wrong:
Nylon (polyamide): This polymer family contains amide linkages and is used in products like nylon fibres and engineering plastics, but it is structurally different from PET.
Acrylic polymer: Acrylic plastics such as PMMA are based on esters of acrylic acid, not on terephthalic acid and ethylene glycol as in PET.
Rayon (regenerated cellulose): Rayon is made from natural cellulose that has been chemically treated, whereas PET is a purely synthetic polyester.
Polyethylene: Although the name of PET starts with polyethylene, simple polyethylene is a different polymer made only from ethene units and contains no ester linkages.

Common Pitfalls:
Some students are misled by the word polyethylene in the full name and may incorrectly think PET is just polyethylene. However, polyethylene terephthalate contains aromatic units and ester linkages that place it firmly in the polyester category. Another confusion is between rayon and polyester because both can be used as textile fibres. Remember that rayon comes from cellulose, while polyester like PET is synthetic and based on ester linkages involving terephthalic acid. Keeping track of the functional groups in the polymer backbone helps avoid such mistakes.

Final Answer:
PET (polyethylene terephthalate), used for making many plastic bottles, is a form of polyester.