Industrial Chemistry MCQs with Answers
Which component in a dye is primarily responsible for its ability to bind to a fabric?
The chromophore group
The solvent medium
The quinoid ring structure
The auxochrome group
Explanation:Auxochromes are functional groups that intensify color and also help the dye to fix onto the fabric by interacting with it.
Bismarck Brown, used for dyeing wool and in boot polishes, belongs to which class of dyes based on its structure?
Triarylmethane Dyes
Nitro Dyes
Indigo Dyes
Azo Dyes
Explanation:Bismarck Brown contains two azo groups (-N=N-) linking three aromatic rings, making it an azo dye.
What is the color of the indicator phenolphthalein in a basic medium?
Explanation:In a basic solution, the structure of phenolphthalein changes to a quinoid form, which imparts a distinct red or pink color.
Vat dyes, such as Indigo, are applied to fabric in a special way. What is the key first step in the vat dyeing process?
Oxidizing the dye into a soluble, colored form.
Treating the fabric first with a metallic salt.
Synthesizing the dye directly within the fabric fibers.
Reducing the dye into a soluble, colorless form.
Explanation:Vat dyes are insoluble, so they must be chemically reduced (often with sodium hydrosulphide) to a soluble, colorless form that can penetrate the fibers.
Malachite Green is an example of a triarylmethane dye. What is the characteristic structural feature of this class?
Two azo groups linking multiple aromatic rings.
A core structure of anthraquinone.
A nitroso group on a naphthalene ring system.
A central carbon bonded to three aromatic rings.
Explanation:This accurately describes the core structure of triarylmethane dyes, where a central carbon is bonded to three aromatic rings, one of which is in the quinoid form.
Which type of dye is applied to a fabric with the help of salts of aluminum or chromium, which form an insoluble complex?
Direct Dyes
Disperse Dyes
Vat Dyes
Mordant Dyes
Explanation:Mordants are metallic salts that are applied to the fabric to form a coordination complex, which in turn binds the dye to the fabric.
Congo Red is prepared by coupling tetrazotised benzidine with two molecules of which compound?
Phenol
Sulphanilic acid
m-diaminobenzene
Naphthionic acid
Explanation:The structure of Congo Red confirms that two molecules of naphthionic acid are coupled with the tetrazotised benzidine.
Azoic dyeing, also known as ingrain dyeing, is a method that involves:
Applying the dye after a chemical reduction process.
Using a metallic salt to bind the dye to the fabric.
Immersing the fabric in a colloidal form of the dye.
Producing an insoluble azo dye within the fabric itself.
Explanation:In this process, the fabric is soaked in a coupling agent and then in a solution of a diazotized amine, forming the final dye 'in-grain' (inside the fabric).
Which of the following is an example of a Nitro dye, containing the -NO₂ group as a chromophore?
Alizarin
Indigo
Methyl Orange
Naphthol Yellow S
Explanation:The structure of Naphthol Yellow S clearly shows nitro groups attached to the naphthalene ring system.
The primary chromophore in azo dyes is the:
-NO₂ group
Carbonyl group (>C=O)
Quinoid structure
-N=N- group
Explanation:This diazo linkage (-N=N-) is the defining chromophore for the entire class of azo dyes.
The polymerization of ethylene to form polyethylene is an example of what type of polymerization?
Condensation polymerization
Copolymerization
Step-growth polymerization
Addition polymerization
Explanation:In this reaction, ethylene monomers add to each other in such a way that the polymer contains all the atoms of the monomer unit. The double bond breaks to form new single bonds.
What is the defining characteristic of a condensation polymer?
Formation from monomers containing double bonds.
The repeating unit and monomer have the same formula.
The product is always a thermoplastic polymer.
Formation with the elimination of a small molecule.
Explanation:This is the hallmark of condensation polymerization, where monomers join together by 'condensing out' a small molecule, such as water.
Nylon-6,6 is a polyamide formed by the condensation reaction between which two monomers?
Ethylene glycol and Terephthalic acid
Vinyl chloride and Vinyl acetate
Phenol and Formaldehyde
Adipic acid and Hexamethylene diamine
Explanation:Nylon-6,6 derives its name from its two six-carbon monomers: adipic acid (a dicarboxylic acid) and hexamethylene diamine (a diamine).
Which of the following is a key characteristic of a thermosetting polymer?
It softens upon heating and can be remolded.
It is made exclusively by addition polymerization.
It has weak forces between its polymer chains.
It hardens upon heating and cannot be softened.
Explanation:Heating causes extensive cross-linking between polymer chains, forming a rigid, infusible solid that cannot be softened by reheating.
Polyvinyl chloride (PVC) is an addition polymer formed from the monomer vinyl chloride, which is synthesized from acetylene and HCl.
1,2-dichloroethane
Trichloroethene
Chloromethane
Chloroethene
Explanation:Vinyl chloride consists of a two-carbon alkene (ethene) with one chlorine atom attached, making its IUPAC name chloroethene.
The reaction by which monomers are converted into polymers is known as:
Hydrolysis
Esterification
Isomerization
Polymerization
Explanation:This is the general term for the process of joining many small molecules (monomers) together to form a very large molecule (polymer).
A polymer synthesized from more than one kind of monomer is called a:
Homopolymer
Thermoset
Addition polymer
Copolymer
Explanation:The prefix 'co-' indicates that it is formed from two or more different monomers working together.
During the addition polymerization of an alkene monomer, what happens to its double bond?
It stays unchanged within the polymer backbone.
It is eliminated from the chain as a small molecule.
It migrates to the terminal end of the polymer.
Its pi bond breaks to form new sigma bonds.
Explanation:The electrons from the weaker pi bond are used to form the strong sigma bonds that constitute the polymer chain.
Which of the following is a common use for PVC?
Stockings and apparel
Packing materials and cable insulation
Fishing lines and brush bristles
Imitation leather and corrugated roofing
Explanation:PVC is a versatile and durable plastic used in a wide range of building and consumer products, including floor covering, roofing, and imitation leather.
A polymer that softens on heating and becomes hard again on cooling is known as:
A thermosetting polymer
An elastomer
A homopolymer
A thermoplastic polymer
Explanation:The prefix 'thermo-' refers to heat, and 'plastic' refers to its ability to be molded. These polymers can be repeatedly softened by heat and hardened by cooling.
Adhesives that are made from sources like vegetable matter, starch, or animal skin are classified as:
Synthetic adhesives
Thermosetting adhesives
Contact adhesives
Natural adhesives
Explanation:These adhesives are derived from biological or inorganic mineral sources and are often referred to as bioadhesives.
How do drying adhesives, such as white glue and rubber cement, harden?
By a chemical reaction between two components.
By cooling down from a molten state.
By exposure to ultraviolet (UV) light.
By the evaporation of their solvent.
Explanation:These adhesives consist of a polymer dissolved or suspended in a solvent. The bond forms as the solvent evaporates.
What is the key application requirement for contact adhesives?
They must be applied while hot.
They must be mixed just before use.
They only need to be applied to a single surface.
They must be applied to both surfaces and dried before joining.
Explanation:Contact adhesives form a bond upon contact after the solvent has evaporated from both coated surfaces.
Hot glue, which is applied with a glue gun, is an example of which type of adhesive?
A natural bioadhesive
A drying adhesive
A UV curing adhesive
A thermoplastic adhesive
Explanation:Also known as hot melt adhesives, these are thermoplastics that are melted, applied, and then harden as they cool to room temperature.
Elastomers, thermoplastics, and thermosetting adhesives are all examples of what broad category of adhesives?
Natural adhesives
Drying adhesives
Hot melt adhesives
Synthetic adhesives
Explanation:These are all classifications of adhesives created through chemical synthesis.
UV and light curing adhesives are composed of low or medium molecular weight:
Starches
Solvents
Elastomers
Resins
Explanation:These adhesives consist essentially of low or medium molecular weight resins that polymerize upon exposure to light.
What is the primary function of an adhesive?
To dissolve the surfaces of two items.
To act as a lubricant between two items.
To provide a decorative coating.
To adhere or bond two items together.
Explanation:This is the fundamental definition of an adhesive – a compound that adheres or bonds two items together.
An example of a natural adhesive derived from starch is:
Epoxy
Super glue (cyanoacrylate)
Rubber cement
Dextrin
Explanation:Dextrin is a type of adhesive made from starch, which is a natural vegetable matter.
Which type of adhesive is popular for crafts due to its ease of use with a wide range of materials?
UV curing adhesives
Natural bioadhesives
Two-part epoxies
Hot melt adhesives
Explanation:Hot melt adhesives have become popular for crafts because of their ease of use and the wide range of common materials to which they can adhere.
The term 'bioadhesives' often refers to which category of adhesives?
Synthetic adhesives
Hot melt adhesives
Drying adhesives
Natural adhesives
Explanation:Natural adhesives derived from biological sources are often referred to as bioadhesives.
The preparation of Methyl Orange involves diazotising which compound first?
Dimethylaniline
p-nitroaniline
Benzidine
Sulphanilic acid
Explanation:The synthesis of Methyl Orange starts with the diazotization of sulphanilic acid.
Which of the following dyes is also well-known as an acid-base indicator?
Malachite Green
Indigo
Alizarin
Phenolphthalein
Explanation:Although classified as a triarylmethane dye, phenolphthalein is better known for its use as an acid-base indicator.
Disperse dyes are primarily used for which type of fabric?
Natural fibers like wool and silk.
Cellulosic fibers like cotton.
All types of fabrics equally.
Modern synthetic fabrics like nylon and polyester.
Explanation:Disperse dyes are used with modern synthetic fabrics such as nylon, orlon, polyester, and cellulose acetate.
The para quinoid structure is the characteristic chromophore in which class of dyes?
Azo Dyes
Nitro Dyes
Indigo Dyes
Anthraquinone Dyes
Explanation:The para quinoid chromophore is present in anthracene-type dyes, such as Alizarin.
What is the function of an auxochrome like -OH or -NH₂ in a dye molecule?
To act as the primary chromophore for color.
To decrease solubility for wash resistance.
To cause the dye molecules to polymerize.
To increase solubility and help bind the dye.
Explanation:The polar auxochrome makes the dye water-soluble and binds it to the fabric by interacting with oppositely charged groups.
Which of the following is NOT a characteristic of an addition polymer?
The monomer units contain double or triple bonds.
No molecule is eliminated during polymerization.
The polymer's backbone consists of carbon atoms.
The polymer is formed in a step-wise manner.
Explanation:Addition polymerization is a chain-growth process. Step-growth is characteristic of condensation polymerization.
The monomers adipic acid and hexamethylene diamine each contain how many carbon atoms?
Adipic acid has 6, hexamethylene diamine has 2.
Both contain 2 carbon atoms.
Adipic acid has 2, hexamethylene diamine has 6.
Both contain 6 carbon atoms.
Explanation:Nylon-6,6 derives its name from its two starting materials, both of which have six carbons.
What type of chemical bond is formed between the monomers in Nylon-6,6?
Ester bond
Ether bond
Carbon-carbon single bond
Amide bond
Explanation:Nylon-6,6 is a polyamide, formed by the reaction between a carboxylic acid and an amine to create an amide linkage (-CONH-).
A polymer made from a single type of monomer, such as polyethylene from ethylene, is called a:
Condensation polymer
Copolymer
Thermoplastic
Homopolymer
Explanation:Polymers which are synthesized from only one kind of monomer are called homopolymers.
The synthesis of vinyl chloride monomer can be achieved by reacting acetylene with which substance in the presence of HgCl₂?
Explanation:Vinyl chloride is obtained from acetylene by treatment with HCl in the presence of HgCl₂.
Which of these is NOT a typical use for Nylon-6,6?
Fibers for clothing and carpeting
Filaments for fishing lines and ropes
Molded objects like gears and bearings
Floor covering and gramophone records
Explanation:Nylon-6,6 is used for fibers, filaments, bristles, and molded objects. Floor covering and gramophone records are uses for PVC.
The primary difference between a thermoplastic and a thermosetting polymer lies in their:
Monomer composition
Molecular weight
Solubility in water
Behavior when heated
Explanation:A thermoplastic softens on heating, while a thermosetting polymer becomes hard on heating and cannot be softened again.
Addition polymerization is also known as:
Step-growth polymerization
Copolymerization
Ionic polymerization
Chain-growth polymerization
Explanation:Addition polymers are also referred to as Chain-Growth Polymers.
Condensation polymerization is also known as:
Chain-growth polymerization
Radical polymerization
Homopolymerization
Step-growth polymerization
Explanation:Condensation polymers are also referred to as step-growth polymers.
Which of these adhesive types works by a physical process rather than a chemical one?
Two-part epoxy
UV curing adhesive
Cyanoacrylate (Super Glue)
Hot melt adhesive
Explanation:Hot melt adhesives are thermoplastics that are applied hot and simply harden as they cool, which is a physical change of state.
Which category of adhesives requires application to both surfaces before they are joined?
Drying adhesives
Hot glue adhesives
Natural adhesives
Contact adhesives
Explanation:Contact adhesives must be applied to both surfaces and allowed some time to dry before the two surfaces are pushed together.
An adhesive made from inorganic mineral sources would be classified as:
Synthetic
Thermoplastic
Thermosetting
Natural
Explanation:Natural adhesives are made from inorganic mineral sources or biological sources.
White glue, a common household and school adhesive, belongs to which class?
Hot melt adhesive
Contact adhesive
UV curing adhesive
Drying adhesive
Explanation:White glue and rubber cements are members of the drying adhesive family, which harden as their solvent evaporates.
What is a major advantage of modern synthetic adhesives over many traditional natural adhesives?
They are always less expensive.
They are more biodegradable.
They are completely non-toxic.
They offer extremely high bond strength.
Explanation:Some modern adhesives are extremely strong and are becoming increasingly important in modern construction and industry.
The process of using a glue gun involves which type of adhesive?
Applying a drying adhesive
Mixing a two-part thermosetting adhesive
Applying a contact adhesive
Melting and applying a hot melt adhesive
Explanation:The glue gun melts the solid hot melt adhesive and allows the liquid to pass through onto the material where it solidifies.
Mordant Green 4 is a dye that contains which chromophore?
Azo group (-N=N-)
Nitro group (-NO₂)
Quinoid ring
Nitroso group (-N=O)
Explanation:The -NO group is the chromophore in Nitroso dyes, and Mordant Green 4 is given as an example.
Para Red was the first azo dye prepared. Its synthesis involves the reaction of diazotized p-nitroaniline with what coupling compound?
Phenol
Aniline
Dimethylaniline
β-naphthol
Explanation:Para red is obtained by the reaction of diazotized p-nitroaniline with β-naphthol.
The color of Methyl Orange changes from yellow in base to red in acid due to:
a hydration reaction.
the breakdown of the azo bond.
the removal of the sulfonate group.
a change in ionic structure.
Explanation:The change in color of Methyl Orange is due to the change in the structure of the ions.
What happens to the colorless, soluble form of Indigo ('Indigo White') when the dyed cloth is hung in the air?
It is reduced back to the insoluble dye.
It polymerizes on the fabric surface.
It reacts with a mordant in the fabric.
It is oxidized back to the insoluble, blue dye.
Explanation:When the cloth is hung in air, the colorless compound is oxidized back to the insoluble colored dye.
The synthesis of phenolphthalein involves heating phthalic anhydride with two moles of what substance?
Aniline
Benzene
Benzoic acid
Phenol
Explanation:Phenolphthalein is prepared by heating phthalic anhydride (1 mole) and phenol (two moles).
Direct dyes, like Martius Yellow, can be applied directly to fibers like wool and silk because:
they are insoluble and get trapped in the fibers.
they undergo a reduction-oxidation cycle.
they are chemically synthesized within the fiber itself.
their auxochromes interact with polar groups in the fiber.
Explanation:A direct dye contains an acidic or basic auxochrome which combines with the opposite polar group present in the chemical structure of the fiber.
Which of the following is NOT a main type of dye when classified by structure according to the provided text?
Azo Dyes
Anthraquinone Dyes
Indigo Dyes
Vat Dyes
Explanation:Azo, Anthraquinone, and Indigo dyes are all classifications by structure. Vat Dyes are a classification based on the method of application.
The chemical stability of a dye, meaning it won't wash out with soap or fade in sunlight, is referred to as its:
Affinity
Solubility
Chromogenicity
Fastness
Explanation:The dye must be 'fast' or chemically stable so that the color will not wash out with soap and water, or fade on exposure to sunlight.
The structure of Alizarin is based on which parent aromatic hydrocarbon?
Naphthalene
Benzene
Phenanthrene
Anthracene
Explanation:Alizarin is a typical anthraquinone dye, which is an anthracene-type dye.
The 'lake' formed during mordant dyeing is:
a solution of the dye in water.
the reduced, colorless form of the dye.
a colloidal dispersion of the dye.
an insoluble complex of fiber, mordant, and dye.
Explanation:The mordant forms an insoluble coordination complex between the fiber and the dye, which appears in the form of lakes.
What is the fundamental difference between homopolymers and copolymers?
The reaction type used for polymerization.
Their thermal behavior when heated.
Their final average molecular weight.
The number of different monomers used.
Explanation:Homopolymers are synthesized from only one kind of monomer, whereas copolymers are prepared from more than one kind.
The process of forming polyethylene can be catalyzed by Ziegler catalysts, which consist of trialkyl aluminum and what other compound?
Sulfuric acid
Mercury(II) chloride
An organic peroxide
Titanium tetrachloride
Explanation:Ziegler Catalysts consist of a trialkyl aluminum and titanium tetrachloride.
In the abbreviated formula for an addition polymer like polyethylene, -[CH₂-CH₂]-n, what does the 'n' represent?
The number of carbons in the monomer.
The number of chains in the sample.
The number of branches on the chain.
The number of repeating monomer units.
Explanation:'n' is the degree of polymerization, indicating that the monomer unit in the brackets is repeated many times to form the long chain polymer.
Which of these is NOT a condensation polymer?
Nylon-6,6
Polyethylene terephthalate (a polyester)
Bakelite (phenol-formaldehyde resin)
Polyvinyl chloride (PVC)
Explanation:PVC is formed by the addition polymerization of vinyl chloride monomers. Nylon and polyesters are explicitly mentioned as condensation polymers.
The key difference in the final structure of thermosetting polymers compared to thermoplastic polymers is the presence of:
Repeating amide linkages.
Aromatic rings in the backbone.
Weak intermolecular forces.
Extensive cross-links.
Explanation:Thermosetting polymers become hard on heating and cannot be softened, which is due to the formation of a rigid, cross-linked 3D network structure.
To create a thermosetting polymer, it is beneficial to use:
a monomer with two functional groups.
a monomer with a carbon-carbon double bond.
a pre-formed linear polymer.
a monomer with three or more functional groups.
Explanation:To form a cross-linked network instead of linear chains, at least one of the monomers must have more than two functional groups to allow for branching. This leads to a thermoset structure.
What is the structural formula of adipic acid, a monomer of Nylon-6,6?
H₂N-(CH₂)₆-NH₂
HOOC-COOH
CH₂=CH-COOH
HOOC-(CH₂)₄-COOH
Explanation:Adipic acid is listed as a reactant for Nylon-6,6 with the formula HOOC(CH₂)₄COOH.
What is the structural formula of hexamethylene diamine, a monomer of Nylon-6,6?
HOOC-(CH₂)₄-COOH
H₂N-(CH₂)₂-NH₂
C₆H₅-NH₂
H₂N-(CH₂)₆-NH₂
Explanation:Hexamethylene diamine is listed as a reactant for Nylon-6,6 with the formula H₂N(CH₂)₆NH₂.
The repeating unit in polyethylene is:
-CH₂-
-(CH₂-CHCl)-
-(CH₃-CH₃)-
-(CH₂-CH₂)-
Explanation:The ethylene monomer (CH₂=CH₂) polymerizes to form the repeating unit -CH₂-CH₂-.
The repeating unit in polyvinyl chloride is:
-(CH₂-CH₂)-
-(CHCl-CHCl)-
-(CCl₂-CH₂)-
-(CH₂-CHCl)-
Explanation:The vinyl chloride monomer (CH₂=CHCl) polymerizes to form the repeating unit -CH₂-CH-Cl.
An adhesive that is a thermoplastic applied in a molten state is known as a:
Drying adhesive
Contact adhesive
Natural adhesive
Hot melt adhesive
Explanation:'Hot melt' adhesives are thermoplastics that are applied hot and allowed to harden as they cool.
Which of the following is an example of a synthetic adhesive?
Starch-based glue
Animal hide glue
Dextrin
Elastomer-based adhesive
Explanation:Elastomers, thermoplastics, and thermosetting adhesives are examples of synthetic adhesives.
The hardening of rubber cement is an example of which process?
Cooling of a thermoplastic
Curing via a chemical reaction
Polymerization initiated by light
Evaporation of a solvent
Explanation:Rubber cement is a member of the drying adhesive family, which hardens as the solvent evaporates.
Which of these is NOT listed as a category of synthetic adhesives?
Elastomers
Thermoplastic adhesives
Thermosetting adhesives
Bioadhesives
Explanation:Elastomers, thermoplastics, and thermosetting adhesives are listed as synthetic. Bioadhesives are referred to as natural adhesives.
What is the key functional group that gives an auxochrome its ability to bind to a protein fiber like wool?
A long hydrocarbon chain
A carbon-carbon double bond
A central metal atom
An acidic or basic group
Explanation:The polar auxochrome binds the dye to the fabric by interaction with the oppositely charged groups of the fiber structure, such as the -NH₂ group of wool.
The reaction to form Nylon-6,6 eliminates a small molecule. What is this molecule?
Ammonia (NH₃)
Hydrogen gas (H₂)
Methanol (CH₃OH)
Water (H₂O)
Explanation:Condensation polymers are formed with the elimination of simple molecules such as H₂O. The reaction image for Nylon-6,6 explicitly shows -H₂O.
If you mix two different types of monomers, one with two acid groups and one with two alcohol groups, what type of polymer will you form?
A polyamide copolymer
An addition homopolymer
A polyethylene copolymer
A polyester copolymer
Explanation:Polyesters are a main type of condensation polymer. The reaction between an acid and an alcohol forms an ester linkage. Since two different monomers are used, it will be a copolymer.
The main purpose of a mordant in dyeing is to:
Dissolve the dye so it can penetrate the fabric.
Reduce the dye to a colorless form.
Intensify the color of the chromophore.
Act as a bridge to bind the dye to the fabric.
Explanation:The mordant forms an insoluble coordination complex between the fiber and the dye and binds the two.
Other Chemistry Topics MCQs
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