MPSC 2025 Prelims Paper-I · Question 67 of 100

Correct — option (3), Polyacrylonitrile. Polyacrylonitrile (PAN) is the synthetic polymer formed by the addition polymerisation of the monomer acrylonitrile, and its commercial fibres — sold under trade names such as Orlon and Acrilan — are specifically engineered to substitute for wool in textiles. PAN fibre shares several of wool's most valued properties: it is soft to the touch, bulky, warm (good thermal insulation), takes dye well, and resists moths and mildew better than natural wool, while typically costing less to produce at scale. Because of this close match in feel and performance, PAN-based acrylic fibre has long been marketed and used as an 'artificial wool' for sweaters, blankets, carpets and cold-weather clothing — precisely the wool-substitute role the question asks about. None of the other three options serve this role: they are real, useful synthetic materials, but each substitutes for something other than wool.

• (1)Dacron — Dacron is a trade name for a polyester fibre made from ethylene glycol and terephthalic acid (the same chemical family as PET). It is prized for crease resistance, durability and its ability to hold shape, and it is commonly blended with cotton to make wrinkle-resistant fabrics, or used in sails, ropes and even Dacron surgical grafts — but it is not marketed or used as a wool substitute; its defining commercial role is as a cotton-blend and general-purpose textile/industrial fibre, not a wool-like fibre.
• (2)Teflon — Teflon is the trade name for polytetrafluoroethylene (PTFE), a polymer of the monomer tetrafluoroethene, valued for its extreme chemical inertness, heat resistance and very low friction (non-stick) surface. Its major uses are non-stick cookware coatings, chemical-resistant linings, gaskets and certain medical grafts — none of which relate to substituting for wool in textiles. PTFE fibre exists for specialised industrial filtration and protective fabrics, but it plays no role as a general wool-like commercial fibre.
• (4)Caprolactam — Caprolactam is the cyclic monomer that, on ring-opening polymerisation, produces Nylon 6, one of the earliest and most widely used synthetic fibres. Nylon fibre is prized for its strength, elasticity and abrasion resistance and is commonly used in ropes, tyre cords, parachutes, stockings and general apparel — historically it was developed and marketed as a substitute for silk, not wool. Caprolactam itself is only the starting monomer, not a wool substitute, and the polymer it forms competes with a different natural fibre altogether.

Synthetic fibres are polymers engineered to reproduce or improve on the properties of natural fibres, and each major synthetic fibre is conventionally associated with the natural fibre it was designed to substitute or compete with: Nylon (from caprolactam, or from adipic acid and hexamethylenediamine for Nylon 6,6) was developed as a silk substitute; polyester (Dacron/Terylene) is prized for crease resistance and is typically blended with cotton; and polyacrylonitrile (PAN), sold as Orlon or Acrilan, was specifically developed to reproduce wool's warmth, bulk and soft handle at lower cost and with better resistance to moths, making it the standard wool substitute among commercial synthetic fibres. Teflon (PTFE), while also a polymer, belongs to a different application category altogether — it is valued for chemical inertness and non-stick, low-friction surfaces rather than for any textile-fibre role.

MPSC's chemistry of polymers questions commonly test this fibre-to-natural-material association table — which synthetic polymer substitutes for which natural fibre — because it is a compact, memorisable set of facts (silk→nylon, cotton→polyester/Dacron, wool→PAN) that is easy to verify but also easy to scramble under exam pressure. Teflon is included here as a plausible-sounding but unrelated polymer to test whether a candidate is recalling the correct wool-substitute fact or simply picking a familiar synthetic-material name.

• Polyacrylonitrile (PAN), marketed as Orlon or Acrilan, is used as a substitute for wool in commercial fibre production.
• Dacron (polyester, from ethylene glycol and terephthalic acid) is prized for crease resistance and is typically blended with cotton.
• Teflon (PTFE, from tetrafluoroethene) is valued for chemical inertness and non-stick surfaces, not as a textile wool substitute.
• Caprolactam is the monomer that polymerises into Nylon 6, historically developed as a silk substitute.
• Each major synthetic fibre is conventionally paired with the natural fibre it was designed to substitute: nylon for silk, polyester for cotton blends, PAN for wool.

• Picking a familiar polymer name (like Teflon) simply because it is well known, without checking its actual application category
• Confusing which synthetic fibre substitutes for which natural fibre — nylon/silk, polyester/cotton, PAN/wool are easy to swap under exam pressure
• Treating caprolactam (a monomer) as if it were itself a finished wool-substitute fibre, rather than recognising it as the precursor to Nylon 6
• Assuming any polymer with fibre applications must be a wool substitute, rather than checking its specific marketed role

MPSC chemistry-of-materials questions frequently test the standard natural-fibre-to-synthetic-substitute pairings (silk→nylon, cotton→polyester, wool→PAN/acrylic), often placing an unrelated but recognisable polymer like Teflon among the options to see whether a candidate can distinguish fibre substitutes from non-textile industrial polymers.

No directly related past PYQ was found.

• practice — not a real PYQ

  Nylon 6, formed by the ring-opening polymerisation of caprolactam, was historically developed as a substitute for which natural fibre ?

  • (a)Cotton
  • (b)Wool
  • (c)Silk
  • (d)Jute

  Answer(c) Silk — nylon was developed and marketed from the 1930s onward as a strong, elastic synthetic substitute for silk, notably in stockings and parachutes.

• practice — not a real PYQ

  Which of the following is the monomer used to produce polyacrylonitrile (PAN), the wool-substitute fibre sold as Orlon or Acrilan ?

  • (a)Ethylene glycol
  • (b)Acrylonitrile
  • (c)Tetrafluoroethene
  • (d)Caprolactam

  Answer(b) Acrylonitrile — polyacrylonitrile is formed by the addition polymerisation of acrylonitrile monomer units, producing a fibre marketed as an artificial wool.