Chemistry

Industrial Chemistry

🏭 Chemistry · Industrial Chemistry
📅 Updated Jan 2026 ⏱️ 30 min read 🎯 High-yield

Industrial Chemistry — Adhesives, Dyes & Polymers

Complete MDCAT Chemistry chapter on industrial chemistry: types of adhesives, types of dyes (chromophores, auxochromes, mordants), and addition vs condensation polymers. Includes 150 solved MCQs with explanations and year-wise past papers.

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⚡Quick Answers to Common Searches

Direct, snippet-optimized answers to the top questions students search about industrial chemistry.

What are adhesives?

Adhesives are substances used to bond two surfaces. Types: natural, thermoplastic, thermosetting, pressure-sensitive, contact, and structural.

What is epoxy resin?

Epoxy is a thermosetting adhesive made from epichlorohydrin + bisphenol A. Cured by a hardener (amine/anhydride). Used in aerospace, automotive, and construction.

What is Super Glue?

Super Glue = cyanoacrylate. Polymerizes rapidly (anionic mechanism) on contact with surface moisture (OH⁻).

What is a chromophore?

A chromophore is an unsaturated group (e.g., -N=N-, -NO₂, >C=O) that absorbs visible light and produces color.

What is an auxochrome?

An auxochrome (e.g., -OH, -NH₂) deepens the color and increases dye affinity for the fiber.

What is a mordant?

A mordant is a metal ion (e.g., Al³⁺, Cr³⁺) that fixes a dye to a fiber by forming a coordination complex (lake).

Direct dye vs reactive dye?

Direct dyes bind by weak forces (moderate fastness). Reactive dyes form covalent bonds with fiber (excellent fastness).

Addition vs condensation polymer?

Addition: no byproduct (e.g., PE, PVC). Condensation: eliminates small molecule like H₂O (e.g., Nylon 6,6; PET).

What is Nylon 6,6?

A polyamide made from adipic acid (6C) + hexamethylenediamine (6C). Both monomers have 6 carbons → "6,6".

What is Terylene (PET)?

A polyester made from ethylene glycol + terephthalic acid. Used in fabrics and bottles.

What is Bakelite?

A thermosetting phenol-formaldehyde resin. Used in electrical switches, plugs, and laminates.

LDPE vs HDPE?

LDPE: branched chains, flexible (bags, films). HDPE: linear chains, rigid (bottles, pipes).

What is Teflon?

Teflon (PTFE) = poly(tetrafluoroethylene). Non-stick, heat-resistant, chemically inert.

What is vulcanization?

Vulcanization = heating rubber with sulfur to form disulfide cross-links. Increases strength and elasticity.

What are the types of dyes?

Direct, acid, basic, disperse, reactive, vat, sulphur, azoic (naphthol), and mordant dyes. Each is specific to certain fiber types.

❓People Also Ask — Industrial Chemistry

Questions students most frequently search about this chapter. Answers are direct and exam-focused.

QWhat are adhesives and how are they classified?
Adhesives are substances used to bond two surfaces together by surface attachment. They are classified as natural (animal/plant-based), thermoplastic (soften on heating, e.g., hot-melt), thermosetting (irreversible cross-linking, e.g., epoxy, phenol-formaldehyde), pressure-sensitive (tacky at room temperature, e.g., Scotch tape), contact (applied to both surfaces), and structural (high strength, replace fasteners).
QWhat is the difference between addition and condensation polymers?
Addition polymers are formed by the repeated addition of unsaturated monomers without the loss of any small molecule (e.g., polyethylene, PVC, PTFE). Condensation polymers are formed by the reaction of bifunctional monomers with the elimination of a small molecule like water or HCl (e.g., Nylon 6,6; Terylene; Bakelite).
QWhat is the role of a chromophore and an auxochrome in a dye?
A chromophore is the unsaturated group (e.g., -N=N-, -NO₂, >C=O) that absorbs visible light and is responsible for the color. An auxochrome is a group (e.g., -OH, -NH₂) that deepens the color and increases the dye's affinity for the fiber.
QWhich type of dye is used for cotton?
Direct dyes, vat dyes (e.g., indigo), and reactive dyes are used for cotton. Direct dyes have natural affinity for cellulose, vat dyes form insoluble pigments inside the fiber, and reactive dyes form covalent bonds with cellulose for excellent wash fastness.
QWhat is the monomer of Nylon 6,6?
Nylon 6,6 is a polyamide made from adipic acid (hexanedioic acid) and hexamethylenediamine. Each monomer contains 6 carbon atoms, giving Nylon 6,6 its name.
QWhy is Teflon used as a non-stick coating?
Teflon (polytetrafluoroethylene, PTFE) has very low surface energy due to the strong C-F bonds and shielded carbon backbone. This makes it chemically inert, heat-resistant, and non-stick, ideal for cookware and industrial bearings.
QWhat is vulcanization?
Vulcanization is the process of heating raw natural rubber with sulfur to form disulfide cross-links between polymer chains. This increases the rubber's strength, elasticity, and resistance to temperature changes.
QWhat is the difference between thermosetting and thermoplastic polymers?
Thermoplastics soften on heating and harden on cooling repeatedly (e.g., polyethylene, PVC). Thermosets form irreversible 3D cross-linked networks and cannot be remelted (e.g., Bakelite, epoxy, melamine-formaldehyde).
QWhat is Bakelite and what is it used for?
Bakelite is a thermosetting plastic made from the condensation of phenol and formaldehyde. It is hard, heat-resistant, and electrically insulating, so it is used in electrical switches, plugs, handles, and laminates.
QWhat is the monomer of natural rubber?
Natural rubber is a polymer of isoprene (2-methyl-1,3-butadiene). The repeating unit is cis-1,4-polyisoprene.
QWhat are reactive dyes and why are they important?
Reactive dyes contain functional groups (e.g., triazine) that form covalent bonds with the hydroxyl groups of cellulose fibers. This covalent linkage provides excellent wash-fastness, making reactive dyes ideal for cotton and other cellulosic fabrics.
QWhat is the difference between cohesive and adhesive failure?
Cohesive failure occurs when the adhesive itself breaks, but remains on both surfaces. Adhesive failure occurs at the interface between the adhesive and the substrate. Good adhesion favors cohesive failure.
QWhat is a copolymer?
A copolymer is a polymer made from two or more different monomers. Examples include SBR (styrene-butadiene rubber), ABS (acrylonitrile-butadiene-styrene), and EVA (ethylene-vinyl acetate).
QWhat is the difference between LDPE and HDPE?
LDPE (Low-Density Polyethylene) has branched chains, making it flexible, transparent, and used in bags and films. HDPE (High-Density Polyethylene) has linear chains with minimal branching, giving it higher crystallinity, rigidity, and use in bottles and pipes.
QHow many MCQs come from Industrial Chemistry in MDCAT?
Industrial Chemistry typically contributes 2–3 MCQs in MDCAT Chemistry. Questions often focus on polymer classification (addition vs condensation), specific polymer examples (Nylon, Terylene, Bakelite), and dye types.
QWhat is the difference between LDPE and HDPE?
LDPE: branched chains → flexible, transparent, used for bags/films. HDPE: linear chains → rigid, opaque, used for bottles/pipes. HDPE has higher crystallinity and density.
QWhat is a biodegradable polymer?
Biodegradable polymers (e.g., PHBV, polylactic acid) can be broken down by microorganisms. They are usually polyesters produced by bacteria or from renewable resources, used in packaging and medical implants.
QWhat is the difference between atactic, isotactic, and syndiotactic polymers?
Atactic: side groups random → amorphous. Isotactic: side groups on the same side → crystalline. Syndiotactic: side groups alternating → semi-crystalline.
QWhat is the role of Ziegler-Natta catalysts?
Ziegler-Natta catalysts (e.g., TiCl₄ + Al(C₂H₅)₃) produce stereoregular polymers like HDPE and isotactic polypropylene, giving higher crystallinity and rigidity.
QWhy is phenol-formaldehyde used in exterior plywood?
Phenol-formaldehyde resin is a thermosetting polymer with excellent water resistance and strength, making it ideal for exterior-grade plywood and marine applications.

📋Syllabus & Learning Outcomes

According to PMDC/PMC MDCAT syllabus, Industrial Chemistry covers:

📝Full Notes — Adhesives, Dyes & Polymers

1. Adhesives – Types & Applications

TypeDescriptionExamples / Uses
Natural adhesivesPlant/animal-based; low bond strengthStarch paste, animal glue (wood, paper)
Thermoplastic adhesivesSoften on heating, harden on cooling; re-workableHot-melt glue (polyethylene, polyamide) – packaging, bookbinding
Thermosetting adhesivesCross-link irreversibly on curing; high strength, heat resistantEpoxy resins, urea-formaldehyde, phenol-formaldehyde – plywood, aircraft, automotive
Pressure-sensitive adhesivesTacky at room temperature; bond on light pressureScotch tape, labels, plasters
Contact adhesivesApplied to both surfaces, dried, then joined; strong instant bondNeoprene cement – laminates, footwear
Structural adhesivesHigh-strength, replace mechanical fastenersEpoxies, acrylics – construction, car bodies

2. Dyes – Types & Uses

Dye ClassApplication methodTypical fibres / Uses
Direct dyesApplied from aqueous solution; no mordantCotton, rayon, paper; easy to use but moderate wash-fastness
Acid dyesAnionic; applied in acidic bathWool, silk, nylon, leather
Basic (cationic) dyesCationic; bright shadesAcrylic fibres, also for biological staining
Disperse dyesInsoluble in water; applied as fine dispersionPolyester, acetate, nylon (synthetic hydrophobic fibres)
Reactive dyesForm covalent bond with fibre → excellent wash-fastnessCotton, wool, silk (cellulosic and protein fibres)
Vat dyesInsoluble; reduced to soluble leuco form, then oxidised on fibreCotton, denim (indigo) – very good fastness
Sulphur dyesApplied like vats; cheap, dark coloursCotton (black, brown)
Azoic (Naphthol) dyesFormed on fibre by couplingCotton (bright reds, oranges)

3. Polymers – Addition & Condensation

Addition Polymers (Chain-growth)

  • Formed by repeated addition of unsaturated monomers (alkenes, substituted alkenes).
  • Mechanism: free radical or ionic; no elimination of small molecules.
PolymerMonomerProperties / Uses
Polyethylene (PE)EtheneLDPE (flexible, film) / HDPE (rigid, bottles)
Polypropylene (PP)PropeneFibres, packaging, automotive parts
Polyvinyl chloride (PVC)Vinyl chloridePipes, window frames, cable insulation
Polystyrene (PS)StyreneDisposable cups, insulation, toys
Polytetrafluoroethylene (PTFE)TetrafluoroetheneNon-stick coatings (Teflon), heat resistant
PolyacrylonitrileAcrylonitrileAcrylic fibres (Orlon) – sweaters, carpets

Condensation Polymers (Step-growth)

  • Formed by reaction between functional groups with elimination of small molecules (water, HCl, etc.).
  • Usually involve two different monomers.
PolymerMonomersLinkage / TypeUses
Nylon 6,6Adipic acid + hexamethylenediamineAmide (polyamide)Fibres, ropes, carpets, engineering plastics
Nylon 6Caprolactam (ring-opening)AmideSimilar to Nylon 6,6
Polyester (PET)Terephthalic acid + ethylene glycolEsterFabrics (Terylene/Dacron), bottles, films
Phenol-formaldehyde (Bakelite)Phenol + formaldehydePhenol-formaldehyde (cross-linked)Electrical fittings, handles, laminates
Urea-formaldehydeUrea + formaldehydeAmino resin (cross-linked)Adhesives, particle board, moulded articles
PolyurethanesDiisocyanate + diolUrethaneFoams, coatings, elastomers

High-Yield Points & Common Traps

  • Thermosetting adhesives: irreversible cross-linking; heat resistant (epoxy, phenol-formaldehyde).
  • Pressure-sensitive adhesives: tacky at room temperature; used in tapes.
  • Direct dyes: applied directly, no mordant; moderate fastness on cotton.
  • Reactive dyes: form covalent bond with fibre; excellent wash-fastness.
  • Disperse dyes: used for polyester and acetate.
  • Addition polymerisation: monomer is alkene; no by-product; e.g., polyethylene, PVC, PTFE (Teflon).
  • Condensation polymerisation: elimination of small molecule (H₂O, HCl); e.g., nylon (amide link), PET (ester link).
  • Polyester: condensation of dicarboxylic acid + diol (PET – Terylene).
  • Bakelite: phenol + formaldehyde; thermosetting, cross-linked.
  • Traps: "All polymers are addition polymers" → False. "Nylon is an addition polymer" → False (condensation). "PVC is a condensation polymer" → False (addition). "Acid dyes are used for cotton" → False (wool/silk/nylon). "All adhesives soften on heating" → False (thermosetting do not).

✅Practice MCQs — Test 1

🧪 Basic Concepts

50 MCQs
1Which of the following is an example of a natural adhesive?
  • A. Epoxy resin
  • B. Polyvinyl acetate (PVA)
  • C. Animal glue (Albumin/Casein)
  • D. Cyanoacrylate
Answer: C. Animal glue
Natural adhesives are derived from animal or plant sources; animal glue from collagen, casein from milk.
2Polyvinyl Acetate (PVA), commonly known as 'white glue,' is primarily used for bonding:
  • A. Metals
  • B. Glass
  • C. Porous materials like wood and paper
  • D. High-temperature engine parts
Answer: C
PVA is water-based, sets by evaporation, and is ideal for porous materials like wood, paper, and fabric.
3Structural adhesives like epoxy resins are characterized by:
  • A. Low strength and high flexibility
  • B. High strength and the ability to bear significant loads
  • C. Being derived from starch
  • D. Requiring no curing time
Answer: B
Epoxies are thermosetting polymers that cure to form a strong, rigid, load-bearing bond, used in aerospace and automotive industries.
4'Super Glue' or 'Krazy Glue' consists of which chemical class?
  • A. Polyurethanes
  • B. Cyanoacrylates
  • C. Phenol-formaldehyde
  • D. Polyamides
Answer: B. Cyanoacrylates
Cyanoacrylates are fast-acting adhesives that polymerize rapidly in the presence of moisture (anionic polymerization).
5Which type of adhesive sets by the evaporation of a solvent?
  • A. Epoxy
  • B. Solvent-based contact cement
  • C. Hot-melt adhesive
  • D. Pressure-sensitive adhesive
Answer: B
Solvent-based adhesives contain a volatile solvent; as it evaporates, the adhesive hardens.
6Pressure-sensitive adhesives (PSAs) are most commonly found in:
  • A. Plywood manufacturing
  • B. Sticky notes and adhesive tapes
  • C. Aeroplane wing assembly
  • D. Ceramic tile fixing
Answer: B
PSAs bond instantly with light pressure (e.g., tapes, labels, sticky notes) via viscoelastic properties.
7Thermosetting adhesives, once cured:
  • A. Can be melted and reshaped
  • B. Form a permanent 3D cross-linked network
  • C. Remain liquid at room temperature
  • D. Are easily dissolved in water
Answer: B
Thermosets undergo irreversible chemical cross-linking, making them insoluble and infusible.
8Hot-melt adhesives are typically applied in a molten state and set by:
  • A. Chemical reaction
  • B. Cooling and solidification
  • C. UV light exposure
  • D. Evaporation of water
Answer: B
Hot-melts are thermoplastics that solidify upon cooling, with no chemical curing.
9Which adhesive is widely used in the plywood industry due to its water resistance?
  • A. Starch paste
  • B. Phenol-formaldehyde resin
  • C. Rubber cement
  • D. Animal glue
Answer: B
Phenol-formaldehyde is a thermosetting resin that provides excellent water resistance and strength for exterior plywood.
10The primary advantage of using adhesives over mechanical fasteners (like bolts) in industry is:
  • A. They are always cheaper
  • B. They distribute stress more evenly across the joint
  • C. They require no surface preparation
  • D. They are easier to remove
Answer: B
Adhesives spread the load over the entire bonded area, reducing stress concentration and improving fatigue resistance.
11A substance that imparts color to a substrate and is resistant to light and washing is a:
  • A. Pigment
  • B. Dye
  • C. Mordant
  • D. Auxochrome
Answer: B. Dye
Dyes are colored substances that chemically bind to or are absorbed by the substrate, providing colorfastness.
12The specific group of atoms in a dye molecule responsible for the absorption of light and production of color is called the:
  • A. Auxochrome
  • B. Chromophore
  • C. Polymer
  • D. Binder
Answer: B. Chromophore
Chromophores are unsaturated groups (e.g., -N=N-, -NO₂, >C=O) that absorb visible light due to π→π* transitions.
13Which of the following is an example of a Chromophore?
  • A. -OH
  • B. -NH₂
  • C. -N=N- (Azo group)
  • D. -COOH
Answer: C. -N=N-
The azo group (-N=N-) is a classic chromophore, found in azo dyes, responsible for intense colors.
14An Auxochrome is a group that:
  • A. Produces color on its own
  • B. Deepens the color and enables the dye to bind to the fiber
  • C. Acts as a solvent
  • D. Bleaches the fabric
Answer: B
Auxochromes (e.g., -OH, -NH₂) are electron-donating or withdrawing groups that shift color and increase dye affinity.
15Acid dyes are typically used to dye animal fibers like wool and silk because they form:
  • A. Covalent bonds with the fiber
  • B. Ionic bonds with the basic groups of the protein fibers
  • C. Hydrogen bonds only
  • D. Metallic complexes
Answer: B
Acid dyes are anionic; they bind to the protonated amino groups (-NH₃⁺) in wool/silk via ionic bonds.
16Direct dyes are primarily used for:
  • A. Synthetic polyesters
  • B. Cellulose-based fibers like cotton and linen
  • C. Plastic toys
  • D. Metal surfaces
Answer: B
Direct dyes have high substantivity for cellulose and are applied directly without a mordant.
17Which type of dye is insoluble in water and must be reduced to a soluble 'leuco' form before application?
  • A. Basic dyes
  • B. Vat dyes (e.g., Indigo)
  • C. Reactive dyes
  • D. Acid dyes
Answer: B. Vat dyes
Vat dyes are water-insoluble; they are reduced in alkaline solution to a soluble leuco form, which is absorbed and then reoxidized.
18Reactive dyes are unique because they form a ___________ bond with the fiber.
  • A. Hydrogen
  • B. Ionic
  • C. Covalent
  • D. Van der Waals
Answer: C. Covalent
Reactive dyes contain groups (e.g., triazine) that form covalent bonds with hydroxyl groups of cellulose, giving excellent wash fastness.
19A substance used to 'fix' a dye to a fabric that otherwise has no affinity for it is called a:
  • A. Developer
  • B. Mordant
  • C. Catalyst
  • D. Plasticizer
Answer: B. Mordant
Mordants (e.g., alum, chromium salts) form coordination complexes with dyes, attaching them to the fiber.
20Disperse dyes are specially designed for:
  • A. Cotton
  • B. Wool
  • C. Hydrophobic synthetic fibers like Polyester and Nylon
  • D. Paper
Answer: C
Disperse dyes are non-ionic and water-insoluble; they sublime or dissolve in the fiber at high temperatures, used for hydrophobic synthetics.
21Basic dyes (cationic dyes) are most effective on:
  • A. Pure cotton
  • B. Acrylic fibers and some modified nylons
  • C. Stainless steel
  • D. Leather
Answer: B
Basic dyes carry positive charge and bind to negatively charged groups (sulfonic or carboxylic) on acrylic fibers.
22Martius Yellow and Aniline Blue are examples of:
  • A. Natural dyes
  • B. Synthetic dyes
  • C. Vat dyes
  • D. Disperse dyes
Answer: B
Martius Yellow and Aniline Blue were among the first synthetic dyes, derived from coal tar.
23The color of a dye is determined by the:
  • A. Weight of the molecule
  • B. Wavelength of light reflected/transmitted
  • C. Temperature of the dye bath
  • D. Amount of water used
Answer: B
Color is perceived as the complementary color of the absorbed wavelength (λ).
24Azo dyes are characterized by the presence of the ___________ group.
  • A. Carbonyl
  • B. Hydroxyl
  • C. Nitrogen-Nitrogen double bond
  • D. Amide
Answer: C
Azo dyes contain one or more -N=N- linkages, making up ~70% of all dyes.
25Which of the following is a natural dye obtained from plants?
  • A. Methyl Orange
  • B. Alizarin (historically from Madder root)
  • C. Phenolphthalein
  • D. Congo Red
Answer: B. Alizarin
Alizarin is a red dye originally extracted from madder root; now synthesized.
26In addition polymerization, the molecular weight of the polymer is:
  • A. Less than the sum of monomers
  • B. Exactly equal to the sum of the masses of the monomers used
  • C. Greater than the sum of monomers
  • D. Half of the total monomer mass
Answer: B
Addition polymerization involves no loss of atoms; the polymer mass equals total monomer mass.
27Which of the following is a characteristic of addition polymers?
  • A. They usually involve monomers with double or triple bonds
  • B. A small molecule like water is eliminated
  • C. They only form 3D networks
  • D. They are always natural
Answer: A
Addition polymers form from unsaturated monomers (e.g., alkenes) via free radical or ionic mechanisms.
28Polyethylene (PE) is formed by the polymerization of:
  • A. Ethyne
  • B. Ethene
  • C. Ethane
  • D. Propene
Answer: B. Ethene
Polyethylene is produced by addition polymerization of ethene (CH₂=CH₂).
29PVC (Polyvinyl Chloride) is an addition polymer of:
  • A. CH₂=CH-Cl
  • B. Cl-CH=CH-Cl
  • C. CH₃-CH₂-Cl
  • D. CCl₄
Answer: A
PVC monomer is vinyl chloride (CH₂=CHCl).
30Teflon (PTFE) is widely used for non-stick coatings. Its monomer is:
  • A. Vinyl chloride
  • B. Tetrafluoroethene
  • C. Styrene
  • D. Acrylonitrile
Answer: B. Tetrafluoroethene
Teflon is poly(tetrafluoroethylene), made from CF₂=CF₂.
31Condensation polymerization differs from addition polymerization because it:
  • A. Requires a catalyst
  • B. Involves the loss of small molecules like H₂O or HCl
  • C. Is much faster
  • D. Only occurs in the gas phase
Answer: B
Condensation polymers form with elimination of small molecules (water, ammonia, HCl).
32Nylon 6,6 is a polyamide formed from:
  • A. Adipic acid and Hexamethylenediamine
  • B. Vinyl acetate and Water
  • C. Terephthalic acid and Ethylene glycol
  • D. Formaldehyde and Urea
Answer: A
Nylon 6,6 is made by condensation of adipic acid (6 carbons) and hexamethylenediamine (6 carbons).
33Terylene (also known as Dacron or PET) is a:
  • A. Polyamide
  • B. Polyester
  • C. Polyether
  • D. Polyalkene
Answer: B. Polyester
Terylene is polyethylene terephthalate (PET), a polyester.
34The monomers of Terylene are:
  • A. Ethylene glycol and Adipic acid
  • B. Ethylene glycol and Terephthalic acid
  • C. Phenol and Formaldehyde
  • D. Styrene and Butadiene
Answer: B
Terylene is made from ethylene glycol and terephthalic acid (or dimethyl terephthalate).
35Bakelite is a thermosetting polymer formed by the condensation of:
  • A. Urea and Formaldehyde
  • B. Phenol and Formaldehyde
  • C. Ethylene and Benzene
  • D. Melamine and Formaldehyde
Answer: B
Bakelite (phenol-formaldehyde) is the first synthetic thermosetting plastic.
36Which of the following is an example of an elastomer?
  • A. Nylon
  • B. Bakelite
  • C. Buna-S (Synthetic rubber)
  • D. Polyvinyl chloride
Answer: C
Elastomers are polymers with high elasticity; Buna-S (styrene-butadiene rubber) is a synthetic elastomer.
37Thermoplastics are polymers that:
  • A. Decompose on heating
  • B. Soften on heating and harden on cooling repeatedly
  • C. Cannot be remolded once shaped
  • D. Are always brittle
Answer: B
Thermoplastics are linear or branched polymers that can be melted and reshaped multiple times.
38Which of the following is a natural polymer?
  • A. Nylon
  • B. Cellulose
  • C. Polyethylene
  • D. Terylene
Answer: B. Cellulose
Cellulose is a natural polysaccharide polymer from plants.
39Low-Density Polyethylene (LDPE) is primarily used for:
  • A. Rigid pipes
  • B. Plastic bags and squeeze bottles
  • C. Bulletproof vests
  • D. Electrical switches
Answer: B
LDPE is flexible and transparent, used for bags, squeeze bottles, and films.
40The process of heating raw rubber with sulfur to improve its strength and elasticity is called:
  • A. Polymerization
  • B. Vulcanization
  • C. Hydrogenation
  • D. Fermentation
Answer: B. Vulcanization
Vulcanization creates cross-links (sulfur bridges) between rubber chains, enhancing strength and elasticity.
41Polystyrene is an addition polymer used for:
  • A. Making ropes
  • B. Food containers and insulation (Styrofoam)
  • C. Non-stick pans
  • D. Car tires
Answer: B
Polystyrene is used for disposable cups, food containers, and expanded polystyrene (Styrofoam) insulation.
42Which polymer is used for making 'unbreakable' cups and plates?
  • A. Polyethylene
  • B. Melamine-formaldehyde resin
  • C. PVC
  • D. Polystyrene
Answer: B
Melamine-formaldehyde is a thermosetting resin that is hard, durable, and heat-resistant, used for dinnerware.
43Nylon 6 (distinct from Nylon 6,6) is produced from the monomer:
  • A. Caprolactam
  • B. Vinyl cyanide
  • C. Isoprene
  • D. Chloroprene
Answer: A. Caprolactam
Nylon 6 is made by ring-opening polymerization of caprolactam (a cyclic amide).
44Synthetic rubber (Neoprene) is a polymer of:
  • A. Isoprene
  • B. Chloroprene
  • C. Butadiene
  • D. Propene
Answer: B. Chloroprene
Neoprene (polychloroprene) is made from chloroprene (2-chloro-1,3-butadiene).
45Which polymer is often used as a substitute for wool in sweaters and blankets?
  • A. PVC
  • B. Orlon (Polyacrylonitrile)
  • C. Bakelite
  • D. Nylon
Answer: B. Orlon
Polyacrylonitrile (PAN) fibers (Orlon, Acrilan) have wool-like feel and are used as synthetic wool.
46In the structure of Nylon 6,6, the '6,6' refers to:
  • A. The number of double bonds
  • B. The number of carbon atoms in each monomer
  • C. The pH at which it is formed
  • D. Its melting point
Answer: B
Each monomer (diamine and diacid) contains 6 carbon atoms.
47Addition polymerization usually involves ___________ mechanism.
  • A. Nucleophilic substitution
  • B. Free radical
  • C. Electrophilic addition
  • D. Elimination
Answer: B. Free radical
Most addition polymerizations (e.g., polyethylene, PVC) proceed via free radical chain mechanism.
48Which of the following is a copolymer?
  • A. Polyethylene
  • B. PVC
  • C. SBR (Styrene-Butadiene Rubber)
  • D. Polypropylene
Answer: C. SBR
SBR is made from two different monomers: styrene and butadiene.
49The repeating unit in a polymer is called a:
  • A. Dimer
  • B. Isomer
  • C. Monomer
  • D. Radical
Answer: C. Monomer
The monomer is the small molecule that repeats to form the polymer chain.
50Which polymer is used in the manufacture of electrical switches and plugs?
  • A. PVC
  • B. Polyethylene
  • C. Bakelite
  • D. Polystyrene
Answer: C. Bakelite
Bakelite is a thermosetting plastic with excellent electrical insulation and heat resistance.

✅Practice MCQs — Test 2

🧪 Advanced Concepts

50 MCQs
1The 'setting' of Cyanoacrylate (Super Glue) is a polymerization reaction initiated by:
  • A. Atmospheric oxygen
  • B. Weak bases or moisture (OH⁻ ions) on the surface
  • C. High temperature
  • D. UV radiation
Answer: B
Cyanoacrylates undergo anionic polymerization initiated by weak bases (e.g., water, hydroxyl ions) on surfaces.
2Epoxy resins are typically formed by the reaction between Epichlorohydrin and:
  • A. Formaldehyde
  • B. Bisphenol A
  • C. Adipic acid
  • D. Ethylene glycol
Answer: B. Bisphenol A
The most common epoxy resin is made from epichlorohydrin and bisphenol A.
3In structural adhesives, 'cohesive failure' occurs when:
  • A. The adhesive detaches from the substrate surface
  • B. The adhesive itself breaks, but remains attached to both surfaces
  • C. The substrate itself breaks
  • D. The adhesive fails to cure
Answer: B
Cohesive failure means the fracture occurs within the adhesive layer, indicating good adhesion.
4Thermoplastic adhesives like Hot-melts are primarily composed of:
  • A. Highly cross-linked networks
  • B. Ethylene-Vinyl Acetate (EVA) copolymers
  • C. Phenolic resins
  • D. Casein proteins
Answer: B. EVA copolymers
EVA copolymers are common hot-melt adhesives due to their good adhesion and flexibility.
5Which of the following describes the 'curing' of a thermosetting adhesive?
  • A. A reversible physical change from liquid to solid
  • B. An irreversible chemical change forming a cross-linked 3D network
  • C. The evaporation of a volatile organic solvent
  • D. The absorption of water from the atmosphere
Answer: B
Curing of thermosets involves chemical cross-linking, irreversible.
6Which adhesive is most suitable for bonding non-polar plastics like Polyethylene without surface treatment?
  • A. Epoxy
  • B. Cyanoacrylate
  • C. Specialized acrylics (though most standard adhesives fail without treatment)
  • D. PVA
Answer: C
Low surface energy plastics like PE require specialized adhesives or surface treatment; standard adhesives fail.
7The strength of an adhesive joint is most significantly influenced by the 'Wetting' of the substrate. Wetting is best when:
  • A. The surface tension of the adhesive is much higher than the substrate
  • B. The surface tension of the adhesive is lower than the surface energy of the substrate
  • C. The substrate is perfectly smooth
  • D. The adhesive is highly viscous
Answer: B
For good wetting, the liquid's surface tension should be less than the substrate's surface energy (contact angle < 90°).
8Anaerobic adhesives (like Loctite) remain liquid in the presence of air but polymerize when:
  • A. Exposed to moisture
  • B. Confined between metal surfaces (excluding oxygen)
  • C. Heated to 100°C
  • D. Mixed with a hardener
Answer: B
Anaerobic adhesives cure in the absence of oxygen, typically between metal surfaces.
9Formaldehyde-based adhesives (Urea-Formaldehyde) are known to release VOCs. Their primary use is in:
  • A. Aerospace industry
  • B. Interior grade plywood and particle board
  • C. Underwater construction
  • D. Medical wound closure
Answer: B
Urea-formaldehyde is used in interior plywood and particle board due to its low cost, but it emits formaldehyde.
10'Contact Cements' are unique because:
  • A. They require high pressure to bond
  • B. Both surfaces are coated and allowed to dry 'tack-free' before being pressed together
  • C. They are only used for glass
  • D. They cure via UV light
Answer: B
Contact cements are applied to both surfaces, dried until tacky, then pressed together for an instant bond.
11Which of the following functions as an 'Auxochrome' by providing a lone pair of electrons to the conjugated system?
  • A. -NO₂
  • B. -N=N-
  • C. -NH₂
  • D. >C=O
Answer: C. -NH₂
Amino (-NH₂) and hydroxyl (-OH) are common auxochromes that donate electrons via resonance, shifting color.
12The color of a dye deepens (shifts to a longer wavelength) when the degree of conjugation increases. This is called a:
  • A. Bathochromic shift (Red shift)
  • B. Hypsochromic shift (Blue shift)
  • C. Hyperchromic effect
  • D. Hypochromic effect
Answer: A
Increased conjugation lowers the HOMO-LUMO gap, causing absorption at longer wavelengths (bathochromic shift).
13In the synthesis of Azo dyes, the 'Coupling Reaction' typically occurs between a diazonium salt and:
  • A. An alkane
  • B. An activated aromatic ring (like phenol or aniline)
  • C. A carboxylic acid
  • D. An alkyl halide
Answer: B
Diazonium salts couple with electron-rich aromatic compounds (phenols, anilines) to form azo dyes.
14Vat dyes like Indigo are insoluble in water. To dye fabric, they are reduced to a soluble form called:
  • A. Chromogen
  • B. Leuco compound
  • C. Mordant
  • D. Lakes
Answer: B. Leuco compound
The leuco form is the reduced, water-soluble version of a vat dye.
15Reactive dyes contain a functional group (like triazine) that reacts with the ___________ group of cellulose fibers.
  • A. Carbonyl
  • B. Hydroxyl (-OH)
  • C. Amide
  • D. Carboxyl
Answer: B
Reactive dyes form covalent bonds with the hydroxyl (-OH) groups of cellulose.
16Which dye requires a 'Mordant' (usually a metal ion like Al³⁺ or Cr³⁺) to form a complex 'Lake' within the fiber?
  • A. Direct dyes
  • B. Adjective/Mordant dyes (e.g., Alizarin)
  • C. Disperse dyes
  • D. Acid dyes
Answer: B
Mordant dyes require a metal ion to form an insoluble colored complex (lake) on the fiber.
17Disperse dyes are applied as a fine aqueous suspension because:
  • A. They are highly ionic
  • B. They are non-polar and have very low water solubility
  • C. They react with water
  • D. They are acidic in nature
Answer: B
Disperse dyes are non-ionic and nearly insoluble in water; they are applied as a dispersion.
18The 'Diazotization' step in dye synthesis involves the reaction of a primary aromatic amine with:
  • A. NaNO₂ and HCl at 0-5°C
  • B. HNO₃ at room temperature
  • C. NH₃ gas
  • D. NaOH and Cl₂
Answer: A
Diazotization: ArNH₂ + NaNO₂ + 2HCl → ArN₂⁺Cl⁻ + NaCl + 2H₂O, at low temperature.
19Which of the following groups is a potent Chromophore?
  • A. -SO₃H
  • B. -OH
  • C. -NO (Nitroso group)
  • D. -CH₃
Answer: C. -NO
Nitroso (-NO) is a chromophore; it absorbs visible light due to n→π* transitions.
20Basic (Cationic) dyes are widely used for 'Acrylic' fibers because the fiber contains:
  • A. Basic groups
  • B. Anionic (acidic) groups that attract the dye cation
  • C. No functional groups
  • D. Only covalent sites
Answer: B
Acrylic fibers have sulfonic acid groups that are negatively charged, attracting cationic basic dyes.
21In 'Step-growth' polymerization (Condensation), the molecular weight of the polymer:
  • A. Increases rapidly at the very beginning
  • B. Increases slowly throughout the reaction and only becomes high at very high conversion
  • C. Is independent of the reaction time
  • D. Decreases as the reaction proceeds
Answer: B
Step-growth polymerization requires high conversion (>99%) to achieve high molecular weight.
22Which of the following is a 'Copolymer' where different monomers are arranged in long alternate sequences?
  • A. Random copolymer
  • B. Block copolymer
  • C. Graft copolymer
  • D. Homopolymer
Answer: B. Block copolymer
Block copolymers have long sequences of one monomer followed by another (e.g., AAAA-BBBB).
23'Tacticity' refers to the spatial arrangement of side groups. A polymer where all side groups are on the same side of the chain is:
  • A. Atactic
  • B. Syndiotactic
  • C. Isotactic
  • D. Stereorandom
Answer: C. Isotactic
Isotactic: all substituents on the same side; syndiotactic: alternating; atactic: random.
24Ziegler-Natta catalysts (e.g., TiCl₄ and Al(C₂H₅)₃) are used to produce:
  • A. Low-Density Polyethylene (LDPE)
  • B. High-Density Polyethylene (HDPE) and Isotactic Polypropylene
  • C. Bakelite
  • D. Nylon 6,6
Answer: B
Ziegler-Natta catalysts produce stereoregular polymers like HDPE and isotactic polypropylene.
25The formation of 'Nylon 6' involves the ring-opening polymerization of:
  • A. Adipic acid
  • B. Caprolactam
  • C. Hexamethylenediamine
  • D. Vinyl cyanide
Answer: B. Caprolactam
Caprolactam is a cyclic amide that ring-opens to form Nylon 6.
26Which polymer is a 'Ladder Polymer' or known for extreme heat resistance used in bulletproof vests?
  • A. PVC
  • B. Kevlar (Aromatic polyamide)
  • C. Polystyrene
  • D. Polypropylene
Answer: B. Kevlar
Kevlar is an aromatic polyamide (aramid) with rigid rod-like chains, used in ballistic vests.
27'Vulcanization' of rubber involves the formation of cross-links between polymer chains using:
  • A. Oxygen bridges
  • B. Sulfur bridges
  • C. Nitrogen bridges
  • D. Hydrogen bonds
Answer: B. Sulfur bridges
Sulfur forms disulfide cross-links between rubber chains during vulcanization.
28Bakelite is formed via a phenol-formaldehyde condensation. The initial linear intermediate formed under acidic conditions is called:
  • A. Resole
  • B. Novolac
  • C. Epoxy
  • D. Polyester
Answer: B. Novolac
Novolac is the linear thermoplastic intermediate formed under acidic conditions; it requires a hardener to cross-link.
29Which of the following is an example of an 'Alternating Copolymer'?
  • A. SBR Rubber
  • B. Nylon 6,6 (technically considered a homopolymer of a repeating salt, but behaves like alternating)
  • C. Styrene-maleic anhydride copolymer
  • D. LDPE
Answer: C
Styrene-maleic anhydride copolymer forms an alternating structure due to strong donor-acceptor interactions.
30High-Density Polyethylene (HDPE) is higher in density than LDPE because:
  • A. It has more branches
  • B. It has almost no branching, allowing chains to pack closely in a crystalline manner
  • C. It has a higher atomic weight
  • D. It contains chlorine atoms
Answer: B
HDPE has linear chains with minimal branching, leading to higher crystallinity and density.
31The Glass Transition Temperature (T_g) is the temperature at which:
  • A. An amorphous polymer changes from a brittle 'glassy' state to a flexible 'rubbery' state
  • B. A polymer melts into a liquid
  • C. A polymer decomposes
  • D. A polymer becomes transparent
Answer: A
T_g is the transition from glassy (hard, brittle) to rubbery (soft, flexible) state.
32Which polymer is synthesized using 'Free Radical Polymerization' with a peroxide initiator?
  • A. Terylene
  • B. Low-Density Polyethylene (LDPE)
  • C. Nylon 6,6
  • D. Bakelite
Answer: B. LDPE
LDPE is produced by free radical polymerization at high pressure and temperature.
33The repeating unit of Natural Rubber is:
  • A. Chloroprene
  • B. Isoprene (2-methyl-1,3-butadiene)
  • C. Butadiene
  • D. Styrene
Answer: B. Isoprene
Natural rubber is polyisoprene (cis-1,4-polyisoprene).
34'Biodegradable' polymers like PHBV are usually:
  • A. Polyesters
  • B. Polyalkenes
  • C. Halogenated polymers
  • D. Polyethers
Answer: A. Polyesters
PHBV (polyhydroxybutyrate-co-valerate) is a biodegradable polyester produced by bacteria.
35Which plastic is identified by the 'Recycling Symbol 3'?
  • A. PET
  • B. HDPE
  • C. PVC
  • D. PS
Answer: C. PVC
Recycling code 3 is for polyvinyl chloride (PVC).
36The strength of Nylon fibers is primarily due to:
  • A. Van der Waals forces
  • B. Extensive Hydrogen bonding between carbonyl and N-H groups
  • C. Ionic attractions
  • D. Metallic bonding
Answer: B
Strong intermolecular hydrogen bonds between amide groups give nylon high tensile strength.
37Which of the following is a 'Graft Copolymer'?
  • A. A-B-A-B-A-B
  • B. A-A-A-B-B-B
  • C. A main chain of A-A-A with side chains of B-B-B
  • D. Random A and B
Answer: C
Graft copolymers have a backbone of one monomer with branches of another.
38Polymethyl methacrylate (PMMA) is a transparent polymer commonly known as:
  • A. Lexan
  • B. Plexiglass/Lucite
  • C. Teflon
  • D. Styrofoam
Answer: B. Plexiglass/Lucite
PMMA is acrylic glass, sold as Plexiglas, Lucite, or Perspex.
39In the manufacture of Polyurethane, the reaction occurs between a di-isocyanate and a:
  • A. Dicarboxylic acid
  • B. Diamine
  • C. Diol (Polyol)
  • D. Dialdehyde
Answer: C. Diol
Polyurethanes are formed by reaction of di-isocyanates with diols (polyols).
40A 'Thermosetting' plastic cannot be remolded because:
  • A. Its chains are too long
  • B. It is held together by weak forces
  • C. It has a dense network of covalent cross-links
  • D. It contains no carbon
Answer: C
Thermosets have a 3D cross-linked network that prevents melting and reshaping.
41Which monomer is used to produce 'Orlon' (Polyacrylonitrile)?
  • A. CH₂=CH-CN
  • B. CH₂=CH-Cl
  • C. CH₂=C(CH₃)-COOCH₃
  • D. CH₂=CH-CH₃
Answer: A
Orlon is polyacrylonitrile, made from acrylonitrile (CH₂=CH-CN).
42The 'Condensation' byproduct in the synthesis of Terylene is:
  • A. HCl
  • B. NH₃
  • C. H₂O (or Methanol, depending on the starting ester)
  • D. CO₂
Answer: C
When made from dimethyl terephthalate and ethylene glycol, methanol is eliminated; from terephthalic acid, water is eliminated.
43Which polymer is used for making surgical sutures that dissolve in the body?
  • A. Polyglactin (PGA/PLA)
  • B. Nylon
  • C. Polyethylene
  • D. PVC
Answer: A. Polyglactin
Polyglactin (Vicryl) and other biodegradable polyesters are used for absorbable sutures.
44'Cold rubber' is a type of SBR produced at low temperatures to:
  • A. Save energy
  • B. Improve its mechanical properties and wear resistance
  • C. Make it transparent
  • D. Increase its solubility
Answer: B
Cold polymerization (5-10°C) produces SBR with better abrasion resistance and mechanical properties.
45Which of the following is a 'Synthetic Polyamide'?
  • A. Terylene
  • B. Nylon
  • C. Protein
  • D. Starch
Answer: B. Nylon
Nylon is a synthetic polyamide; proteins are natural polyamides.
46What is the role of a 'Plasticizer' in polymers like PVC?
  • A. To increase the melting point
  • B. To make the polymer more flexible and less brittle by reducing intermolecular forces
  • C. To act as a pigment
  • D. To speed up polymerization
Answer: B
Plasticizers (e.g., phthalates) separate polymer chains, increasing flexibility and reducing brittleness.
47'Chain-transfer agents' are added during polymerization to:
  • A. Speed up the reaction
  • B. Control and limit the molecular weight of the polymer
  • C. Initiate the chain
  • D. Stop the reaction completely
Answer: B
Chain transfer agents (e.g., mercaptans) terminate growing chains and start new ones, controlling molecular weight.
48Melamine-Formaldehyde resin is highly resistant to heat and moisture, making it ideal for:
  • A. Plastic bags
  • B. Dinnerware and laminate surfaces (Formica)
  • C. Ropes
  • D. Car tires
Answer: B
Melamine-formaldehyde is used for durable dinnerware, laminates, and countertops.
49Which of the following is a 'Fluoropolymer'?
  • A. PVC
  • B. Teflon
  • C. Bakelite
  • D. Polystyrene
Answer: B. Teflon
Teflon (PTFE) is a fluoropolymer with C-F bonds, known for non-stick properties.
50The conversion of a monomer into a polymer involves a decrease in:
  • A. Molecular weight
  • B. Entropy
  • C. Boiling point
  • D. Density
Answer: B. Entropy
Polymerization reduces the number of molecules, decreasing entropy (ΔS negative).

✅Practice MCQs — Test 3

🧪 Exam-Level Questions

50 MCQs
1According to the Young-Dupré equation, for an adhesive to exhibit 'perfect wetting' on a substrate, the contact angle (θ) must be:
  • A. 90°
  • B. 0°
  • C. 180°
  • D. 45°
Answer: B. 0°
Perfect wetting occurs when the liquid spreads completely (θ = 0°), giving maximum adhesion.
2The 'Interphase' in an adhesive joint differs from the 'Interface' because it:
  • A. Is a 2D mathematical plane
  • B. Is a 3D region with properties distinct from both the bulk adhesive and the substrate
  • C. Only exists in natural glues
  • D. Is the term for the adhesive before it cures
Answer: B
The interphase is a 3D region where the adhesive and substrate interact, with properties different from either bulk.
3In the curing of Polyurethane adhesives, the highly reactive Isocyanate group (-N=C=O) typically reacts with a hydroxyl group to form a:
  • A. Peptide bond
  • B. Urethane (Carbamate) linkage
  • C. Ester bond
  • D. Ether bond
Answer: B
Isocyanate + alcohol → urethane (carbamate) linkage.
4Why do Cyanoacrylates fail to bond effectively to Acidic surfaces?
  • A. The acid causes the glue to evaporate
  • B. The polymerization mechanism is anionic; protons (H⁺) neutralize the initiating nucleophile
  • C. Acids increase the surface energy too much
  • D. They only bond to metallic oxides
Answer: B
Cyanoacrylate polymerization is initiated by bases (OH⁻); acids inhibit initiation.
5The 'Critical Surface Tension' (γ_c) of a substrate is a measure of:
  • A. Its tensile strength
  • B. The maximum surface tension a liquid can have and still spread on that surface
  • C. Its melting point
  • D. The adhesive's viscosity
Answer: B
γ_c is the surface energy of a solid; liquids with surface tension below γ_c will wet the surface.
6Which phenomenon explains why adhesives like Gecko-tape work without chemical bonding?
  • A. Covalent cross-linking
  • B. Capillary action
  • C. Van der Waals forces amplified by massive contact surface area (setae)
  • D. Ionic attraction
Answer: C
Gecko adhesion is due to van der Waals forces from millions of microscopic hairs (setae).
7In epoxy systems, a 'Hardener' like Diethylenetriamine (DETA) acts as a:
  • A. Catalyst only
  • B. Chain terminator
  • C. Stoichiometric cross-linking agent that becomes part of the polymer network
  • D. Solvent
Answer: C
Amine hardeners react stoichiometrically with epoxy groups, becoming part of the cross-linked network.
8The transition of an adhesive from a liquid to a solid 'glassy' state without a change in chemical composition is a:
  • A. Chemical cure
  • B. Physical setting (like in Hot-melts)
  • C. Condensation
  • D. Vulcanization
Answer: B
Hot-melt adhesives set by physical cooling (no chemical reaction).
9'Tack' in pressure-sensitive adhesives is a visco-elastic property. It is defined as:
  • A. The ultimate bond strength after 24 hours
  • B. The ability to form a bond of measurable strength immediately upon contact under low pressure
  • C. Resistance to UV light
  • D. The temperature at which it melts
Answer: B
Tack is the 'stickiness' or immediate bond formation upon light pressure.
10Which of the following describes 'Adhesive Failure'?
  • A. The substrate breaks
  • B. The adhesive breaks internally
  • C. The bond fails at the boundary between the adhesive and the substrate
  • D. The adhesive fails to undergo an exothermic reaction
Answer: C
Adhesive failure occurs at the adhesive-substrate interface (loss of adhesion).
11The color of a dye is a result of electronic transitions between the HOMO and LUMO. As the conjugated system increases, the energy gap (ΔE):
  • A. Increases, causing a Blue Shift
  • B. Decreases, causing a Red Shift (Bathochromic)
  • C. Remains constant
  • D. Disappears
Answer: B
Conjugation lowers ΔE, shifting absorption to longer wavelengths (red shift).
12Why is Phenolphthalein colorless in acidic solution?
  • A. The molecule is destroyed
  • B. The central carbon is sp³ hybridized, breaking the conjugation between the three rings
  • C. It lacks auxochromes
  • D. It reflects all wavelengths
Answer: B
In acid, the lactone form has an sp³ carbon that breaks conjugation, causing colorless.
13In 'Mordant Dyeing,' the metal ion (like Cr³⁺) acts as a Lewis Acid to form a chelate complex with the dye. This complex is called a:
  • A. Leuco-dye
  • B. Lake
  • C. Chromogen
  • D. Auxochrome
Answer: B. Lake
The insoluble dye-metal complex is called a lake.
14Azo dyes are sensitive to pH changes because the azo group (-N=N-) can be:
  • A. Oxidized to NO₂
  • B. Protonated, changing the resonance and color of the molecule
  • C. Converted to an alkane
  • D. Sublimated
Answer: B
Protonation of azo nitrogen alters electron distribution, changing color (e.g., methyl orange).
15Which of the following is a 'Fluorescent Brightening Agent' (Optical Brightener)?
  • A. They absorb visible light and reflect IR
  • B. They absorb UV light and re-emit it in the visible blue spectrum
  • C. They are highly acidic dyes
  • D. They bleach the stains away
Answer: B
Optical brighteners absorb UV (invisible) and emit blue light, making fabrics appear whiter.
16The 'Exhaustion' of a dye bath refers to:
  • A. The dye becoming unstable
  • B. The proportion of the dye that has moved from the solution onto the fiber
  • C. The temperature of the bath dropping
  • D. The technician becoming tired
Answer: B
Exhaustion is the percentage of dye absorbed from the bath by the fiber.
17'Substantivity' in dyeing refers to:
  • A. The cost of the dye
  • B. The natural affinity of a dye for a specific fiber without the need for a mordant
  • C. The toxicity of the dye
  • D. The speed of the reaction
Answer: B
Substantivity is the direct attraction between dye and fiber.
18Which specific transition is usually responsible for the color in organic azo dyes?
  • A. σ → σ*
  • B. n → σ*
  • C. π → π*
  • D. d → d
Answer: C. π → π*
π→π* transitions in conjugated systems (including azo groups) give intense colors.
19Why do Vat dyes (like Indigo) have excellent wash-fastness?
  • A. They form ionic bonds
  • B. They are trapped physically inside the fiber as insoluble pigments after oxidation
  • C. They are highly soluble in water
  • D. They are applied at 0°C
Answer: B
After reduction and application, the dye is reoxidized to an insoluble pigment trapped in the fiber.
20A 'Hypsochromic Shift' in a dye's absorption spectrum is often caused by:
  • A. Increasing conjugation
  • B. Removal of an auxochrome or change in solvent polarity
  • C. Increasing the concentration
  • D. Heating the dye
Answer: B
Hypsochromic shift (blue shift) moves absorption to shorter wavelength, often due to decreased conjugation.
21According to the Carothers Equation, for a step-growth polymer (like Nylon) to reach a high degree of polymerization (X̄_n), the extent of reaction (p) must be:
  • A. At least 0.50
  • B. Exactly 0.75
  • C. Very close to 1.00 (e.g., >0.99)
  • D. Independent of the number of monomers
Answer: C
X̄_n = 1/(1-p); for high DP, p must approach 1 (e.g., 0.99 gives DP=100).
22The 'Polydispersity Index' (PDI) is the ratio of M_w to M_n. For a perfectly monodisperse polymer, the PDI is:
  • A. 0
  • B. 1
  • C. ∞
  • D. 2
Answer: B. 1
Monodisperse polymers have M_w = M_n, so PDI = 1.
23'Living Polymerization' is a form of addition polymerization where:
  • A. The polymer is made of biological cells
  • B. The chain termination and transfer steps are eliminated
  • C. The reaction never stops, even after the monomer is consumed
  • D. Only natural monomers are used
Answer: B
Living polymerization has no termination, allowing control of molecular weight and narrow PDI.
24Which property increases significantly when a polymer is 'Oriented' (stretched) during fiber spinning?
  • A. Chemical resistance
  • B. Tensile strength in the direction of the fiber axis
  • C. Melting point
  • D. Solubility
Answer: B
Orientation aligns polymer chains along the fiber axis, increasing crystallinity and tensile strength.
25A 'Spherulite' in a polymer sample represents:
  • A. A single polymer molecule
  • B. A microscopic, spherical semi-crystalline region
  • C. A defect or air bubble
  • D. The initiator molecule
Answer: B
Spherulites are supermolecular structures formed by lamellar crystals growing radially from a nucleus.
26Why does Atactic Polystyrene have a lower density and transparency compared to Isotactic Polystyrene?
  • A. It has a higher molecular weight
  • B. Its random side-group arrangement prevents efficient chain packing/crystallization
  • C. It contains more impurities
  • D. It is an addition polymer
Answer: B
Atactic PS is amorphous (non-crystalline) due to random side groups, while isotactic PS can crystallize.
27In the Free Radical Polymerization of Styrene, the use of Benzoyl Peroxide serves as:
  • A. The monomer
  • B. The initiator, which undergoes homolytic cleavage to form radicals
  • C. The solvent
  • D. The chain transfer agent
Answer: B
Benzoyl peroxide decomposes to form free radicals that initiate polymerization.
28'Kevlar' is much stronger than 'Nylon 6,6' because it is an Aromatic Polyamide (Aramid). The aromatic rings:
  • A. Make the polymer liquid
  • B. Provide high chain stiffness and facilitate extensive inter-chain H-bonding
  • C. Prevent the polymer from burning
  • D. Increase solubility
Answer: B
Rigid aromatic rings increase chain stiffness, and amide groups form extensive hydrogen bonds, giving high strength.
29The 'Auto-acceleration' (Trommsdorff effect) in radical polymerization is caused by:
  • A. A sudden increase in temperature
  • B. An increase in viscosity that hinders chain termination more than chain propagation
  • C. The addition of more initiator
  • D. The depletion of monomer
Answer: B
As viscosity increases, termination slows, causing a rapid increase in reaction rate and molecular weight.
30Which polymer would you expect to have the highest T_g (Glass Transition Temperature)?
  • A. Polyethylene (flexible chain)
  • B. Polypropylene
  • C. Poly(vinyl chloride) (due to the large, polar Cl atom)
  • D. Poly(tetrafluoroethene)
Answer: C
Bulky or polar side groups (Cl) restrict chain rotation, increasing T_g.
31Condensation polymers like PET (Terylene) are generally 'degraded' in the presence of strong acids or bases via:
  • A. Oxidation
  • B. Hydrolysis
  • C. Addition
  • D. Sublimation
Answer: B. Hydrolysis
Polyesters are susceptible to hydrolysis, especially in basic conditions (saponification).
32'Syndiotactic' polymers have side groups arranged:
  • A. Randomly
  • B. On the same side
  • C. On alternating sides of the polymer backbone
  • D. In clusters
Answer: C
Syndiotactic: substituents alternate sides; isotactic: same side; atactic: random.
33The 'Melt Flow Index' (MFI) is an indirect measure of molecular weight. A high MFI indicates:
  • A. High molecular weight and high viscosity
  • B. Low molecular weight and low viscosity
  • C. High crystallinity
  • D. High density
Answer: B
High MFI means the polymer flows easily, indicating lower molecular weight and lower viscosity.
34Which of the following is a 'Conducting Polymer' (due to its extensively delocalized π-electron system)?
  • A. Polyethylene
  • B. Polyacetylene (when doped)
  • C. PVC
  • D. Nylon
Answer: B. Polyacetylene
Polyacetylene, after doping, becomes electrically conductive due to conjugated π-bonds.
35In the production of 'Expandable Polystyrene' (Styrofoam), the 'blowing agent' is typically:
  • A. Air
  • B. A low-boiling hydrocarbon like Pentane
  • C. Water
  • D. Carbon black
Answer: B. Pentane
Pentane or other volatile hydrocarbons are used as blowing agents to create foam.
36'Copolymerization' is often used to 'internally plasticize' a polymer. This means:
  • A. Making it harder
  • B. Lowering the T_g by introducing a 'softer' comonomer into the chain
  • C. Increasing the melting point
  • D. Making it toxic
Answer: B
Incorporating a flexible comonomer lowers T_g, making the polymer softer and more flexible.
37Which linkage is found in 'Glyptal' resins (used in paints)?
  • A. Amide
  • B. Ester (it is a cross-linked polyester)
  • C. Ether
  • D. Urethane
Answer: B
Glyptal resins are polyesters made from glycerol and phthalic anhydride.
38The 'Degree of Polymerization' (DP) is calculated as:
  • A. Total mass / Monomer mass
  • B. Monomer mass / Total mass
  • C. Number of moles of initiator
  • D. Number of double bonds
Answer: A
DP = Molar mass of polymer / Molar mass of monomer.
39Why is 'Neoprene' (Polychloroprene) superior to Natural Rubber in industrial hoses?
  • A. It is cheaper
  • B. The chlorine atom provides superior resistance to oils, solvents, and oxidation
  • C. It is more biodegradable
  • D. It is a liquid
Answer: B
Chlorine makes neoprene resistant to oils, fuels, and weathering.
40A 'Graft Copolymer' of ABS (Acrylonitrile Butadiene Styrene) provides a balance of:
  • A. Transparency and weight
  • B. Hardness, strength, and impact resistance
  • C. Solubility and color
  • D. Acidity and basicity
Answer: B
ABS combines the rigidity of styrene-acrylonitrile with the toughness of polybutadiene.
41The specific gravity of a polymer usually ___________ as crystallinity increases.
  • A. Decreases
  • B. Increases
  • C. Stays the same
  • D. Becomes zero
Answer: B
Crystalline regions pack more tightly, increasing density.
42Which polymer is used for 'Heat-shrink' tubing?
  • A. Cross-linked Polyethylene
  • B. Pure PVC
  • C. Bakelite
  • D. Teflon
Answer: A. Cross-linked Polyethylene
Cross-linked polyethylene has memory; when heated, it shrinks to its original dimensions.
43The 'Inhibition Period' in polymerization is caused by the presence of:
  • A. Too much monomer
  • B. Impurities like Oxygen or Hydroquinone that react with free radicals
  • C. High pressure
  • D. Catalyst
Answer: B
Inhibitors (e.g., hydroquinone) scavenge free radicals, delaying the start of polymerization.
44'Cold Flow' (Creep) is a common disadvantage of:
  • A. Thermosets
  • B. Thermoplastics (especially those used above their T_g)
  • C. Fibers
  • D. Ceramics
Answer: B
Thermoplastics can deform under constant load over time (creep), especially above T_g.
45Which of the following is a 'Network Polymer'?
  • A. HDPE
  • B. Melamine-Formaldehyde
  • C. Nylon 6
  • D. Polystyrene
Answer: B. Melamine-Formaldehyde
Melamine-formaldehyde is a thermosetting network polymer (3D cross-linked).
46'SBR' (Styrene-Butadiene Rubber) is primarily a:
  • A. Homopolymer
  • B. Random Copolymer
  • C. Block Copolymer
  • D. Graft Copolymer
Answer: B. Random Copolymer
SBR is a random copolymer of styrene and butadiene.
47The monomer for 'Synthetic Silk' (Rayon) is technically:
  • A. An amino acid
  • B. Glucose (since it is regenerated cellulose)
  • C. Adipic acid
  • D. Isoprene
Answer: B. Glucose
Rayon is made from cellulose, which is a polymer of glucose.
48Which reaction describes the formation of 'Urea-Formaldehyde' resin?
  • A. Addition
  • B. Condensation followed by cross-linking
  • C. Radical
  • D. Redox
Answer: B
Urea-formaldehyde is a condensation polymer that can further cross-link.
49'Photo-degradable' polymers often contain ___________ groups that absorb UV light and cause chain scission.
  • A. Ether
  • B. Carbonyl (>C=O)
  • C. Alkane
  • D. Hydroxyl
Answer: B. Carbonyl
Carbonyl groups can undergo Norrish type reactions upon UV exposure, breaking polymer chains.
50'Terylene' is also known as 'Dacron' in the US and 'Lavsan' in Russia. Its IUPAC-like name is:
  • A. Poly(ethylene terephthalate)
  • B. Poly(vinyl acetate)
  • C. Poly(amide 6,6)
  • D. Poly(methyl acrylate)
Answer: A
Terylene is polyethylene terephthalate (PET).

📄Past Paper MCQs

📅 Actual MDCAT / NUMS Questions

50 MCQs
1Nylon 6,6 is a condensation polymer made from hexamethylenediamine and:
MDCAT 2022, UHS 2017
  • A. Adipic acid
  • B. Phthalic acid
  • C. Terephthalic acid
  • D. Maleic acid
Answer: A. Adipic acid
Nylon 6,6 is made from adipic acid (6 carbons) and hexamethylenediamine (6 carbons).
2The repeating unit in Natural Rubber is:
NUMS 2023, MDCAT 2015
  • A. Chloroprene
  • B. Isoprene
  • C. Butadiene
  • D. Neoprene
Answer: B. Isoprene
Natural rubber is polyisoprene (cis-1,4-polyisoprene).
3Terylene (Dacron) is a polyester formed by the reaction of ethylene glycol and:
UHS 2019, ETEA 2021
  • A. Adipic acid
  • B. Terephthalic acid
  • C. Benzoic acid
  • D. Phthalic acid
Answer: B. Terephthalic acid
Terylene is polyethylene terephthalate (PET) from ethylene glycol and terephthalic acid.
4Which of the following is a thermosetting polymer?
MDCAT 2020, NUMS 2018
  • A. Polyethylene
  • B. PVC
  • C. Bakelite
  • D. Polystyrene
Answer: C. Bakelite
Bakelite (phenol-formaldehyde) is a thermosetting plastic.
5The monomer of Polyvinyl Chloride (PVC) is:
UHS 2014, MDCAT 2021
  • A. CH₂=CH₂
  • B. CH₂=CHCl
  • C. CHCl=CHCl
  • D. CH₂=CCl₂
Answer: B. CH₂=CHCl
PVC monomer is vinyl chloride (CH₂=CHCl).
6Which small molecule is typically eliminated during the formation of Nylon 6,6?
NUMS 2020, MDCAT 2018
  • A. NH₃
  • B. HCl
  • C. H₂O
  • D. CO₂
Answer: C. H₂O
Condensation polymerization releases water.
7Teflon (PTFE) is an addition polymer of:
UHS 2016, MDCAT 2023
  • A. Monofluoroethene
  • B. Difluoroethene
  • C. Tetrafluoroethene
  • D. Vinyl fluoride
Answer: C. Tetrafluoroethene
PTFE is made from tetrafluoroethylene (CF₂=CF₂).
8The process of heating raw rubber with sulfur is called:
MDCAT 2019, NUMS 2021
  • A. Polymerization
  • B. Vulcanization
  • C. Hydrogenation
  • D. Sulphonation
Answer: B. Vulcanization
Vulcanization cross-links rubber with sulfur.
9Which polymer is used as a substitute for wool?
UHS 2013, MDCAT 2022
  • A. PVC
  • B. Orlon (Polyacrylonitrile)
  • C. Nylon
  • D. Teflon
Answer: B. Orlon
Polyacrylonitrile fibers (Orlon, Acrilan) mimic wool.
10Bakelite is formed by the reaction between Formaldehyde and:
NUMS 2022, UHS 2015
  • A. Urea
  • B. Phenol
  • C. Melamine
  • D. Ethylene glycol
Answer: B. Phenol
Bakelite is phenol-formaldehyde resin.
11Low-Density Polyethylene (LDPE) is produced by _________ polymerization.
MDCAT 2020, ETEA 2019
  • A. Free radical
  • B. Ionic
  • C. Coordination
  • D. Condensation
Answer: A. Free radical
LDPE is made by free radical polymerization at high pressure.
12Which of the following is a copolymer?
NUMS 2019, MDCAT 2021
  • A. Polypropylene
  • B. SBR (Styrene-Butadiene Rubber)
  • C. PVC
  • D. Polystyrene
Answer: B. SBR
SBR is a copolymer of styrene and butadiene.
13Starch and Cellulose are polymers of:
UHS 2011, MDCAT 2023
  • A. Fructose
  • B. Glucose
  • C. Sucrose
  • D. Maltose
Answer: B. Glucose
Both are polysaccharides of glucose.
14In Nylon 6,6, the two '6's represent:
MDCAT 2017, UHS 2021
  • A. Number of oxygen atoms
  • B. Number of carbon atoms in the monomers
  • C. Number of nitrogen atoms
  • D. Melting point in hundreds
Answer: B
Each monomer contains 6 carbon atoms.
15Polypropylene is an addition polymer of:
NUMS 2021, MDCAT 2014
  • A. CH₂=CH₂
  • B. CH₃-CH=CH₂
  • C. CH₃-CH₂-CH₃
  • D. CH₂=C(CH₃)₂
Answer: B
Polypropylene monomer is propylene (CH₃-CH=CH₂).
16Which polymer is used for making non-stick kitchenware?
UHS 2012, MDCAT 2018
  • A. PVC
  • B. Teflon
  • C. Bakelite
  • D. Polystyrene
Answer: B. Teflon
Teflon (PTFE) has non-stick properties.
17Which of the following is NOT a synthetic polymer?
NUMS 2023, MDCAT 2016
  • A. Nylon
  • B. Terylene
  • C. Cellulose
  • D. Polystyrene
Answer: C. Cellulose
Cellulose is a natural polymer from plants.
18Buna-S rubber is a polymer of 1,3-Butadiene and:
MDCAT 2020, UHS 2019
  • A. Acrylonitrile
  • B. Styrene
  • C. Vinyl chloride
  • D. Isoprene
Answer: B. Styrene
Buna-S (SBR) is styrene-butadiene rubber.
19Which polymer is used in making electrical switches?
UHS 2013, MDCAT 2022
  • A. Polyethylene
  • B. PVC
  • C. Bakelite
  • D. Nylon
Answer: C. Bakelite
Bakelite is a thermosetting insulator used for switches.
20The catalyst used in the manufacture of HDPE (High-Density Polyethylene) is:
NUMS 2020, MDCAT 2017
  • A. Fe/Mo
  • B. Ziegler-Natta catalyst
  • C. V₂O₅
  • D. Ni
Answer: B. Ziegler-Natta
Ziegler-Natta catalysts produce linear HDPE.
21A group that deepens the color and increases the affinity of a dye for fiber is called:
MDCAT 2022, NUMS 2021
  • A. Chromophore
  • B. Auxochrome
  • C. Mordant
  • D. Polymer
Answer: B. Auxochrome
Auxochromes are electron-donating/withdrawing groups that affect color and binding.
22Which of the following is an example of a Chromophore?
UHS 2018, MDCAT 2020
  • A. -OH
  • B. -NH₂
  • C. -N=N-
  • D. -COOH
Answer: C. -N=N-
The azo group (-N=N-) is a chromophore.
23Indigo is a famous example of a _________ dye.
MDCAT 2021, UHS 2015
  • A. Acid
  • B. Basic
  • C. Vat
  • D. Direct
Answer: C. Vat
Indigo is a vat dye, applied in reduced leuco form.
24Reactive dyes are unique because they form a _________ bond with the fiber.
NUMS 2022, MDCAT 2023
  • A. Ionic
  • B. Hydrogen
  • C. Covalent
  • D. Van der Waals
Answer: C. Covalent
Reactive dyes form covalent bonds with cellulose.
25Which type of dye is used for protein fibers like wool and silk?
UHS 2016, MDCAT 2019
  • A. Basic dyes
  • B. Acid dyes
  • C. Disperse dyes
  • D. Vat dyes
Answer: B. Acid dyes
Acid dyes bind ionically to the protonated amino groups of proteins.
26Methyl Orange is an example of an:
NUMS 2020, MDCAT 2017
  • A. Azo dye
  • B. Anthraquinone dye
  • C. Phthalic dye
  • D. Nitro dye
Answer: A. Azo dye
Methyl orange is an azo dye with -N=N- linkage.
27Disperse dyes are mainly used for:
MDCAT 2022, ETEA 2020
  • A. Cotton
  • B. Wool
  • C. Synthetic fibers like Polyester
  • D. Silk
Answer: C
Disperse dyes are used for hydrophobic synthetics like polyester.
28A substance that fixes a dye to the fabric is called:
UHS 2014, NUMS 2018
  • A. Catalyst
  • B. Mordant
  • C. Auxochrome
  • D. Binder
Answer: B. Mordant
Mordants form complexes with dyes to attach them to fibers.
29Direct dyes are mostly used for:
MDCAT 2021, UHS 2011
  • A. Nylon
  • B. Cotton (Cellulose)
  • C. Terylene
  • D. Acrylic
Answer: B. Cotton
Direct dyes have high substantivity for cellulose fibers.
30Which of the following is a natural dye?
NUMS 2021, MDCAT 2015
  • A. Alizarin
  • B. Congo Red
  • C. Martius Yellow
  • D. Malachite Green
Answer: A. Alizarin
Alizarin was originally from madder root.
31The intensity of color in a dye increases with:
MDCAT 2023, UHS 2019
  • A. Decreasing conjugation
  • B. Increasing conjugation
  • C. Increasing molecular weight
  • D. Decreasing temperature
Answer: B
More conjugation increases color intensity (bathochromic shift).
32Basic dyes are most suitable for:
NUMS 2023, MDCAT 2020
  • A. Wool
  • B. Acrylic and modified nylons
  • C. Cotton
  • D. Pure polyester
Answer: B
Basic dyes bind to negatively charged groups on acrylic fibers.
33The solvent-soluble form of a Vat dye is called:
MDCAT 2022, UHS 2017
  • A. Chromogen
  • B. Leuco form
  • C. Lake
  • D. Pigment
Answer: B. Leuco form
The reduced leuco form is water-soluble.
34Which of the following is an Auxochrome?
NUMS 2022, MDCAT 2016
  • A. -NO₂
  • B. -OH
  • C. -CO-
  • D. -C=C-
Answer: B. -OH
Hydroxyl (-OH) is an auxochrome.
35Azo dyes contain the linkage:
UHS 2013, MDCAT 2018
  • A. -N=O
  • B. -N=N-
  • C. -NH-NH-
  • D. -NO₂
Answer: B. -N=N-
Azo dyes contain the -N=N- azo group.
36Polyvinyl Acetate (PVA) is widely used as an adhesive for:
MDCAT 2022, UHS 2015
  • A. Metals
  • B. Wood and Paper
  • C. Plastic to Plastic
  • D. Glass
Answer: B. Wood and Paper
PVA white glue is used for porous materials like wood and paper.
37Epoxy resins are characterized by their high:
NUMS 2021, MDCAT 2020
  • A. Water solubility
  • B. Structural strength and chemical resistance
  • C. Volatility
  • D. Elasticity
Answer: B
Epoxies are strong, chemically resistant structural adhesives.
38'Super Glue' is chemically known as:
MDCAT 2021, UHS 2018
  • A. Polyvinyl acetate
  • B. Cyanoacrylate
  • C. Phenol-formaldehyde
  • D. Urea-formaldehyde
Answer: B. Cyanoacrylate
Super glue is cyanoacrylate adhesive.
39Adhesives that set by cooling from a molten state are called:
NUMS 2022, MDCAT 2019
  • A. Solvent-based
  • B. Hot-melt adhesives
  • C. Pressure-sensitive
  • D. Structural
Answer: B. Hot-melt adhesives
Hot-melt adhesives are thermoplastic and set upon cooling.
40Animal glues (like Casein) are examples of:
UHS 2016, MDCAT 2014
  • A. Synthetic adhesives
  • B. Natural adhesives
  • C. Inorganic adhesives
  • D. Thermosetting adhesives
Answer: B. Natural adhesives
Animal glues are natural adhesives derived from animal proteins.
41Pressure-sensitive adhesives (PSAs) are used in:
MDCAT 2023, NUMS 2020
  • A. Plywood
  • B. Adhesive tapes and sticky notes
  • C. Car engines
  • D. Aerospace bonding
Answer: B
PSAs are used in tapes, labels, and sticky notes.
42Which adhesive is most commonly used in the plywood industry?
UHS 2017, MDCAT 2021
  • A. Starch
  • B. Urea-Formaldehyde or Phenol-Formaldehyde
  • C. Rubber cement
  • D. Cyanoacrylate
Answer: B
Urea- and phenol-formaldehyde resins are used for plywood.
43The primary mechanism of PVA glue setting is:
MDCAT 2022, NUMS 2019
  • A. Chemical cross-linking
  • B. Evaporation of water (solvent loss)
  • C. UV radiation
  • D. Cooling
Answer: B
PVA is water-based; it sets as water evaporates.
44Epoxy adhesives consist of a resin and a:
UHS 2018, MDCAT 2023
  • A. Solvent
  • B. Hardener (Curing agent)
  • C. Pigment
  • D. Plasticizer
Answer: B. Hardener
Epoxies require a hardener (amine or anhydride) to cure.
45Which of the following is a disadvantage of natural adhesives?
MDCAT 2020, NUMS 2021
  • A. They are too expensive
  • B. Susceptibility to moisture and microbial attack
  • C. They are toxic
  • D. They cannot be used on paper
Answer: B
Natural adhesives (e.g., animal glue) can degrade in moist conditions.
46Structural adhesives are designed to:
UHS 2019, MDCAT 2022
  • A. Be easily removed
  • B. Support heavy loads and replace mechanical fasteners
  • C. Be used only on clothes
  • D. Stay liquid forever
Answer: B
Structural adhesives bear loads and can replace rivets/welds.
47Contact cement is usually applied to:
MDCAT 2021, NUMS 2023
  • A. Only one surface
  • B. Both surfaces to be bonded
  • C. The edges only
  • D. Molten metal
Answer: B
Contact cement is applied to both surfaces and dried before pressing.
48Resole and Novolac are intermediates in the production of:
UHS 2012, MDCAT 2017
  • A. Nylon
  • B. Bakelite (Phenol-formaldehyde)
  • C. Terylene
  • D. PVC
Answer: B
Novolac and resole are precursors to phenol-formaldehyde resins.
49Polyurethane adhesives are known for being:
NUMS 2020, MDCAT 2023
  • A. Very brittle
  • B. Highly flexible and water-resistant
  • C. Water-soluble
  • D. Natural products
Answer: B
Polyurethanes are flexible, durable, and water-resistant.
50The 'Tack' of an adhesive refers to its:
MDCAT 2022, UHS 2016
  • A. Color
  • B. Instantaneous 'stickiness' upon contact
  • C. Final strength after 7 days
  • D. Melting point
Answer: B. Instantaneous stickiness
Tack is the immediate stickiness or initial bond strength.

🔍Direct Search Queries — Industrial Chemistry

Exact search terms students use on Google for this chapter. Click any to jump to the relevant section:

industrial chemistry MDCAT notes types of adhesives thermosetting vs thermoplastic adhesive epoxy resin structure cyanoacrylate super glue mechanism PVA glue properties hot melt adhesive uses pressure sensitive adhesive types of dyes chemistry chromophore vs auxochrome mordant dyeing reactive dyes covalent bond vat dyes indigo reduction disperse dyes polyester direct dyes cotton azo dye synthesis diazotization addition vs condensation polymer polyethylene monomer PVC polyvinyl chloride Teflon PTFE monomer Nylon 6,6 monomers adipic acid Terylene PET polyester Bakelite phenol formaldehyde LDPE vs HDPE difference what is industrial chemistry difference between addition and condensation polymerization what are the types of dyes what is vulcanization of rubber what is a copolymer industrial chemistry MCQs with answers industrial chemistry MCQs pdf polymers MCQs MDCAT MDCAT past papers industrial chemistry UHS industrial chemistry MCQs NUMS polymers past papers industrial chemistry class 12 notes polymers chapter notes MDCAT adhesives dyes polymers summary

❔Frequently Asked Questions

What are adhesives and how are they classified?
Adhesives are substances used to bond two surfaces together by surface attachment. They are classified as natural (animal/plant-based), thermoplastic (soften on heating, e.g., hot-melt), thermosetting (irreversible cross-linking, e.g., epoxy, phenol-formaldehyde), pressure-sensitive (tacky at room temperature, e.g., Scotch tape), contact (applied to both surfaces), and structural (high strength, replace fasteners).
What is the difference between addition and condensation polymers?
Addition polymers are formed by the repeated addition of unsaturated monomers without the loss of any small molecule (e.g., polyethylene, PVC, PTFE). Condensation polymers are formed by the reaction of bifunctional monomers with the elimination of a small molecule like water or HCl (e.g., Nylon 6,6; Terylene; Bakelite).
What is the role of a chromophore and an auxochrome in a dye?
A chromophore is the unsaturated group (e.g., -N=N-, -NO₂, >C=O) that absorbs visible light and is responsible for the color. An auxochrome is a group (e.g., -OH, -NH₂) that deepens the color and increases the dye's affinity for the fiber.
Which type of dye is used for cotton?
Direct dyes, vat dyes (e.g., indigo), and reactive dyes are used for cotton. Direct dyes have natural affinity for cellulose, vat dyes form insoluble pigments inside the fiber, and reactive dyes form covalent bonds with cellulose for excellent wash fastness.
What is the monomer of Nylon 6,6?
Nylon 6,6 is a polyamide made from adipic acid (hexanedioic acid) and hexamethylenediamine. Each monomer contains 6 carbon atoms, giving Nylon 6,6 its name.
Why is Teflon used as a non-stick coating?
Teflon (polytetrafluoroethylene, PTFE) has very low surface energy due to the strong C-F bonds and shielded carbon backbone. This makes it chemically inert, heat-resistant, and non-stick, ideal for cookware and industrial bearings.
What is vulcanization?
Vulcanization is the process of heating raw natural rubber with sulfur to form disulfide cross-links between polymer chains. This increases the rubber's strength, elasticity, and resistance to temperature changes.
What is the difference between thermosetting and thermoplastic polymers?
Thermoplastics soften on heating and harden on cooling repeatedly (e.g., polyethylene, PVC). Thermosets form irreversible 3D cross-linked networks and cannot be remelted (e.g., Bakelite, epoxy, melamine-formaldehyde).
What is Bakelite and what is it used for?
Bakelite is a thermosetting plastic made from the condensation of phenol and formaldehyde. It is hard, heat-resistant, and electrically insulating, so it is used in electrical switches, plugs, handles, and laminates.
What is the monomer of natural rubber?
Natural rubber is a polymer of isoprene (2-methyl-1,3-butadiene). The repeating unit is cis-1,4-polyisoprene.
What are reactive dyes and why are they important?
Reactive dyes contain functional groups (e.g., triazine) that form covalent bonds with the hydroxyl groups of cellulose fibers. This covalent linkage provides excellent wash-fastness, making reactive dyes ideal for cotton and other cellulosic fabrics.
What is the difference between cohesive and adhesive failure?
Cohesive failure occurs when the adhesive itself breaks, but remains on both surfaces. Adhesive failure occurs at the interface between the adhesive and the substrate. Good adhesion favors cohesive failure.
What is a copolymer?
A copolymer is a polymer made from two or more different monomers. Examples include SBR (styrene-butadiene rubber), ABS (acrylonitrile-butadiene-styrene), and EVA (ethylene-vinyl acetate).
What is the difference between LDPE and HDPE?
LDPE (Low-Density Polyethylene) has branched chains, making it flexible, transparent, and used in bags and films. HDPE (High-Density Polyethylene) has linear chains with minimal branching, giving it higher crystallinity, rigidity, and use in bottles and pipes.
How many MCQs come from Industrial Chemistry in MDCAT?
Industrial Chemistry typically contributes 2–3 MCQs in MDCAT Chemistry. Questions often focus on polymer classification (addition vs condensation), specific polymer examples (Nylon, Terylene, Bakelite), and dye types.
What is a biodegradable polymer?
Biodegradable polymers (e.g., PHBV, polylactic acid) can be broken down by microorganisms. They are usually polyesters produced by bacteria or from renewable resources, used in packaging and medical implants.
What is the difference between atactic, isotactic, and syndiotactic polymers?
Atactic: side groups random → amorphous. Isotactic: side groups on the same side → crystalline. Syndiotactic: side groups alternating → semi-crystalline.
What is the role of Ziegler-Natta catalysts?
Ziegler-Natta catalysts (e.g., TiCl₄ + Al(C₂H₅)₃) produce stereoregular polymers like HDPE and isotactic polypropylene, giving higher crystallinity and rigidity.
Why is phenol-formaldehyde used in exterior plywood?
Phenol-formaldehyde resin is a thermosetting polymer with excellent water resistance and strength, making it ideal for exterior-grade plywood and marine applications.
What is the difference between a homopolymer and a copolymer?
A homopolymer is made from a single type of monomer (e.g., polyethylene from ethene). A copolymer is made from two or more different monomers (e.g., SBR from styrene and butadiene).

📚Other Chemistry Chapters

1
Atomic Structure
2
Chemical Bonding
3
Hydrocarbons
4
Alkyl Halides
5
Alcohols & Phenols
6
Aldehydes & Ketones
7
Carboxylic Acids
8
Macromolecules

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