The monomer of nylon is

Analysis

The question asks for the monomer (or one of the repeating units) used in the synthesis of Nylon. Nylon is a synthetic polymer known as a polyamide.

Concept Explanation

Nylon is produced through a process called condensation polymerization. Specifically, the most common form, Nylon-6,6, is formed by the reaction between two distinct monomers:

1. Hexanedioic acid (also known as Adipic acid)
2. Hexamethylenediamine (1,6-diaminohexane)

In a condensation reaction, the carboxylic acid group (-COOH) of the hexanedioic acid reacts with the amine group (-NH₂) of the diamine, releasing a molecule of water for every bond formed.

Step-by-Step Solution

1. Evaluate Option A (Hydroxybenzene): This is phenol. It is used in the production of resins like Bakelite, not Nylon.
2. Evaluate Option B (Hexanedioic acid): This is a six-carbon dicarboxylic acid. It provides the "acid" part of the amide linkage in Nylon-6,6. It is a fundamental building block for this polymer.
3. Evaluate Option C (Benzene-1,4-dicarboxylic acid): Also known as terephthalic acid, this is used in the production of polyesters like Terylene (Dacron), not Nylon.
4. Evaluate Option D (Ethane-1,2-diol): This is ethylene glycol, which is also used in the production of polyesters (like Terylene) when reacted with terephthalic acid.

Since Nylon-6,6 requires a dicarboxylic acid, Hexanedioic acid is the correct monomer listed among the options.

Conclusion

Hexanedioic acid is essential for the formation of the amide bonds that characterize the structure of nylon.

Exam Tip

When studying polymers, remember this simple rule:

• Polyamides (Nylon): Formed from a Dicarboxylic acid + a Diamine.
• Polyesters (Terylene): Formed from a Dicarboxylic acid + a Diol. Always look for the "acid" component in the options when asked about Nylon!