This section contains multiple choice questions. Each question has 4 choices (a), (b), (c) and (d), out of which ONLY ONE is correct. Which of the following is an example of phenol-formaldehyde resin? (a) Perlon (b) Nylon-6,6 (c) Bakelite (d) Dacron

Phenol-formaldehyde resins, also known as phenolic resins, are synthetic polymers formed through the reaction of phenol and formaldehyde. These resins have a wide range of applications, including molded products, adhesives, and coatings. They are generally hard, durable, and have good heat and chemical resistance.

Let's briefly analyze each option to determine which one is an example of phenol-formaldehyde resin: (a) Perlon: Perlon is a brand name for a specific type of synthetic polyamide material, commonly known as nylon. This material is not formed from the reaction of phenol and formaldehyde, so it is not a phenol-formaldehyde resin. (b) Nylon-6,6: Nylon-6,6 is a specific type of polyamide made from the condensation polymerization of hexamethylenediamine and adipic acid. Like Perlon, it is not formed from the reaction of phenol and formaldehyde, so it is not a phenol-formaldehyde resin. (c) Bakelite: Bakelite is a resin formed by the polymerization of phenol and formaldehyde. Due to its composition, it falls under the category of phenol-formaldehyde resins. Bakelite is a thermosetting plastic, which means it cannot be melted and re-molded once cured. This resin is known for its durability, heat resistance, and insulation properties. (d) Dacron: Dacron is a brand name for a specific type of polyester material, also known as polyethylene terephthalate (PET). It is not formed from the reaction of phenol and formaldehyde, so it is not a phenol-formaldehyde resin.

Comparing all the options, we can see that Bakelite (option c) is the only resin formed by the reaction of phenol and formaldehyde. Therefore, the correct answer is (c) Bakelite.