The monomers of glyptal are:

Question

Accepted Answer

Glyptal is a type of polyester resin, and its monomers are ethylene glycol and phthalic acid. Here's a detailed explanation of why Option 3 is correct and why the other options are incorrect:

1. **Explanation for Option 3 (Correct Answer):**
   - **Ethylene Glycol and Phthalic Acid:** Glyptal is synthesized through a polycondensation reaction between ethylene glycol and phthalic acid (or its anhydride form, phthalic anhydride). Ethylene glycol is a diol, and phthalic acid is a dicarboxylic acid. When these two compounds react, they form ester linkages, resulting in the formation of a polyester resin. Glyptal is commonly used in paints, coatings, and as an insulating material due to its excellent adhesive and protective properties.

2. **Explanation for why other options are incorrect:**

- **Option 1: Phenol and Formaldehyde**
     - Phenol and formaldehyde are the monomers for phenolic resins, such as Bakelite, not glyptal. These resins are formed through a condensation reaction between phenol and formaldehyde, resulting in a thermosetting polymer. This is distinctly different from the polyester structure of glyptal.

- **Option 2: Styrene**
     - Styrene is a monomer used to produce polystyrene, a different type of polymer. Polystyrene is a thermoplastic polymer, whereas glyptal is a thermosetting polyester resin. Styrene does not react with phthalic acid or ethylene glycol to form glyptal.

- **Option 4: Ethylene Glycol and Terephthalic Acid**
     - Ethylene glycol and terephthalic acid are the monomers for polyethylene terephthalate (PET), not glyptal. PET is another type of polyester, commonly used in fibers for clothing and containers for liquids and foods. While both PET and glyptal are polyesters, they are made from different dicarboxylic acids (terephthalic acid for PET and phthalic acid for glyptal).

In conclusion, Option 3 is the correct answer because glyptal is specifically synthesized from ethylene glycol and phthalic acid, forming a polyester resin with unique properties suitable for its applications.