Which one of the following statements is NOT true about polymers and their general characteristics?

Introduction / Context:
Polymers are ubiquitous in everyday life, from plastics and synthetic fibres to natural materials like DNA and proteins. Understanding what polymers are and how they are structured is central to polymer chemistry and materials science. This question asks you to identify which statement about polymers is not true, testing your ability to distinguish accurate descriptions of polymer characteristics from misleading or exaggerated claims.

Given Data / Assumptions:

• Polymers are made from monomer units linked together, usually forming long chains.
• They are often described as macromolecules due to their large molecular weights.
• Some polymers have regular, repeating structures; others may have some randomness but still follow patterns of repeating units.
• Polymers can be natural or synthetic.

Concept / Approach:
A polymer is defined as a large molecule consisting of many repeating structural units derived from monomer molecules. These repeating units are arranged in chains or networks, giving polymers their macromolecular nature. While copolymers may have sequences involving more than one type of repeating unit, the structure is not a completely random arrangement of atoms; it still follows specific patterns dictated by the monomers and polymerisation mechanism. Therefore, any statement that suggests polymers are always completely random arrangements of atoms, without repeating structural patterns, is not an accurate description. The other statements correctly describe polymers as large, high molecular weight macromolecules that may be natural or synthetic.

Step-by-Step Solution:
Step 1: Examine statement A, which says that polymers are large molecules composed of repeating small monomer units. This matches the basic definition of polymers and is true. Step 2: Consider statement B, which describes polymers as macromolecules with very high molecular weights. This is also correct because polymers usually contain hundreds or thousands of monomer units, giving large molecular masses. Step 3: Evaluate statement C, which claims that polymers are always complex molecules composed of completely random sequences of atoms with no repeating structural pattern. This is misleading because polymers are defined by repeating structural units; even random copolymers follow a pattern of monomer units rather than completely random atomic arrangements. Step 4: Review statement D, which notes that polymers can be natural, like cellulose and proteins, or synthetic, like polyethylene and nylon. This accurately reflects the range of polymers found in nature and industry. Step 5: Recognise that statement C is the one that is not true, while the others describe real properties of polymers. Statement E, which says all statements are true, must therefore also be false.

Verification / Alternative check:
Consider examples of polymers. Polyethylene is made from repeating –CH2– units derived from ethene; its structure is clearly not a random mix of atoms but a regular chain. Proteins are polymers of amino acids linked by peptide bonds in a specific sequence governed by genetic information. Even in copolymers where two or more monomers are used, the backbone still consists of repeating monomer derived units and follows particular sequence patterns (random, alternating, block, or graft). No standard polymer is described as a completely random collection of atoms; the concept of repeating units is fundamental. This confirms that statement C is not true.

Why Other Options Are Wrong:
Statement A is true because it accurately describes the basic structure of polymers as made up of monomer units. Statement B is true because polymers are indeed macromolecules with high molecular weights. Statement D is true because examples of natural polymers include cellulose, starch, and proteins, while synthetic polymers include PVC, polystyrene, and nylon. Statement E claims that all statements are true, but since statement C is false, statement E cannot be correct either. The only explicitly incorrect scientific claim is the idea that polymers always have completely random sequences of atoms with no repeating patterns.

Common Pitfalls:
Some learners may misinterpret the word "complex" in statement C and think that because polymers are large and can have complicated structures, the statement must be correct. They may ignore the phrase "completely random sequences of atoms with no repeating structural pattern," which contradicts the fundamental definition of a polymer. Another pitfall is quickly choosing "All of the above" without carefully evaluating each statement. To avoid these mistakes, always focus on the core characteristics of polymers: high molecular weight and presence of repeating structural units derived from monomers.

Final Answer:
The statement that is NOT true about polymers is that polymers are always complex molecules composed of completely random sequences of atoms with no repeating structural pattern.