Remember that rubbers (like Buna-S, Buna-N, Neoprene) are always elastomers.
Resins (like Bakelite, Melamine, Urea-formaldehyde) are thermosetting polymers.
This allows you to quickly eliminate wrong options.
Step 1: Understanding the Question:
This is a matching question from polymer chemistry.
We need to match the classification of polymers based on molecular forces (List-I) with their corresponding commercial examples (List-II).
Step 2: Key Formula or Approach:
Polymers are classified into four categories based on intermolecular forces:
1. Elastomers: Weakest intermolecular forces (elastic nature).
2. Fibres: Strongest intermolecular forces (high tensile strength, hydrogen bonding).
3. Thermoplastics: Intermediate intermolecular forces (linear/branched, can be melted repeatedly).
4. Thermosetting polymers: Cross-linked networks (harden permanently on heating).
Step 3: Detailed Explanation:
• Let us match each item:
• A. Elastomer:
Styrene-butadiene polymer (Buna-S) is a synthetic rubber. It has weak intermolecular forces that allow it to stretch and return to its original shape.
Matches with III.
• B. Fibre:
Dacron (Terylene) is a polyester. It possesses strong intermolecular forces (dipole-dipole and hydrogen bonding), giving it high tensile strength suitable for making fabrics.
Matches with I.
• C. Thermosetting polymer:
Urea-formaldehyde resin is a highly cross-linked, three-dimensional network polymer. Once heated and molded, it undergoes chemical changes and cannot be remelted.
Matches with IV.
• D. Thermoplastic polymer:
Polyvinyl chloride (PVC) is a linear polymer that softens on heating and hardens on cooling, allowing it to be recycled and reshaped.
Matches with II.
• Combining the matches: A-III, B-I, C-IV, D-II.
Step 4: Final Answer:
The correct matching is (C) A-III, B-I, C-IV, D-II.
