A Level Chemistry OCR Practice Exam

What is the definition of a polymer?

1. A long molecular chain built up from small molecules

2. A short molecular structure with fixed atoms

3. A rigid and unchangeable compound

4. A simple ion in a solution

The correct answer is: A long molecular chain built up from small molecules

A polymer is defined as a long molecular chain that is composed of repeating structural units typically derived from small molecules known as monomers. These monomers undergo a process called polymerization, where they chemically bond together to form the larger, complex structure of the polymer. This chain-like structure gives polymers their unique properties, such as flexibility, durability, and the ability to be molded into various shapes. In contrast, the other options do not accurately capture the essence of what a polymer is. A short molecular structure with fixed atoms doesn't allow for the extended chain characteristic of polymers. The idea of a rigid and unchangeable compound fails to reflect the diverse nature of polymers, which can be both rigid and flexible depending on their type and applications. Lastly, a simple ion in a solution does not represent a polymer, as it lacks the molecular complexity and long-chain characteristics that define polymers. Thus, the correct choice effectively encompasses the fundamental structure and formation of polymers.