This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Polymerization”.
1. Which type of polymer will be formed if the substituent group is –C6H5?
a) Polythene
b) Polypropylene
c) Polystyrene
d) Polyvinyl chloride
View Answer
Explanation: Polystyrene will be formed if the substituent group is –C6H5. It is a synthetic aromatic polymer made from the monomer styrene. Polystyrene can be solid or foamed.
2. Select the incorrect statement from the following option.
a) Addition polymerisation requires the presence of double bond in monomer
b) No by-product is formed in addition polymerisation
c) In addition polymerisation, growth of chain is at one active centre
d) In addition polymerisation, polymer MW rises steadily throughout the reaction
View Answer
Explanation: In addition polymerisation, high MW polymer is formed at once. All the other options are correct. Addition polymerisation requires the presence of a double bond in monomer and no by-product is formed. In addition polymerisation, growth of chain is at one active centre.
3. Select the incorrect statement from the following option.
a) Condensation polymerisation requires two reactive functional groups to be present at both ends of the monomer
b) No by-product is formed in condensation polymerisation
c) In condensation polymerisation, growth of chain occurs at minimum of the two active centres
d) In condensation polymerisation, polymer MW rises steadily throughout the reaction
View Answer
Explanation: Generally a by-product is formed in condensation polymerisation. All the other options are correct.
Condensation polymerisation requires two reactive functional groups to be present at both ends of the monomer and growth of chain occurs at a minimum of the two active centres. In condensation polymerisation, polymer MW rises steadily throughout the reaction.
4. The Ziegler Natta catalyst is formed between _____________
a) Triethyl aluminium and titanium halide
b) Triethyl aluminium and silver halide
c) Triethyl aluminium and platinum halide
d) Triethyl aluminium and carbon halide
View Answer
Explanation: The Ziegler Natta catalyst is formed between triethyl aluminium and titanium halide. It is named after Karl Ziegler and Giulio Natta, used in the synthesis of polymers of 1-alkenes (alpha-olefins).
5. The co-polymers having branched structures in which the monomer segments on the backbone and branches differ are called ____________
a) Alternate
b) Graft
c) Random
d) Block
View Answer
Explanation: The co-polymers having branched structures in which the monomer segments on the backbone and branches differ are called graft.
6. Which of the following act as an initiator in free-radical polymerisation?
a) Grignard reagent
b) Lewis acids
c) Benzoyl peroxide
d) Potassium amide
View Answer
Explanation: Benzoyl peroxide act as an initiator in free-radical polymerisation. Benzoyl peroxide is used as an acne treatment, for bleaching flour, hair and teeth, for cross-linking polyester resins, and for many other purposes.
7. Which of the following act as a catalyst in anionic polymerisation?
a) Grignard reagent
b) Lewis acids
c) Benzoyl peroxide
d) AIBN
View Answer
Explanation: Grignard reagent act as a catalyst in anionic polymerisation. The Grignard reaction is an organo-metallic chemical reaction in which alkyl, vinyl, or aryl-magnesium halides, CH3MgI (Grignard reagents) add to a carbonyl group in an aldehyde or ketone.
8. The temperature at which the ionic polymerisation is carried out is ____________
a) 1000C
b) 500C
c) -1000C
d) 00C
View Answer
Explanation: The temperature at which the ionic polymerisation is carried out is 00C. Ionic polymerization is a chain-growth polymerization in which active centers are ions or ion pairs.
9. Radical polymerisation is not sensitive to changes in the polarity.
a) True
b) False
View Answer
Explanation: Radical polymerisation is not sensitive to changes in the polarity. Free radical polymerization is a method of polymerization by which a polymer forms by the successive addition of free radical building blocks.
10. Which of the following monomer cannot be polymerised by radical polymerisation?
a) Butadiene
b) Isobutylene
c) Vinyl chloride
d) Acrylates
View Answer
Explanation: Isobutylene monomer can be polymerised by cationic polymerisation. Butadiene, vinyl chloride and acrylates can be polymerised by radical polymerization.
11. The polymerisation in which propagating centers do not undergo either transfer or termination reactions is called ____________
a) Addition polymerisation
b) Co-polymerisation
c) Living polymerisation
d) Dead polymerisation
View Answer
Explanation: The polymerisation in which propagating centers do not undergo either transfer or termination reactions is called living polymerisation. Polymerization is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks.
12. In esterification, the nucleophile is _________ and the leaving group is ____________
a) Alcohol, ester
b) Ester, alcohol
c) Water, alcohol
d) Alcohol, water
View Answer
Explanation: In esterification, the nucleophile is alcohol and the leaving group is water. Esterification is the general name for a chemical reaction in which two reactants (typically an alcohol and an acid) form an ester as the reaction product.
13. The reverse of esterification is ____________
a) Hydrolysis
b) Condensation
c) Polymerisation
d) Centrifugation
View Answer
Explanation: The reverse of esterification is hydrolysis. Hydrolysis is a reaction involving the breaking of a bond in a molecule using water. The reaction mainly occurs between an ion and water molecules and often changes the pH of a solution.
14. Which of the following is used for making cold drink bottles, magnetic recording tapes and housings for coffee machines?
a) Ethylene glycol
b) Polyethylene terephthalate
c) Hexamethylene diamine
d) Styrene butadiene
View Answer
Explanation: Polyethylene terephthalate (PET) is used for making cold drink bottles, magnetic recording tapes and housings for coffee machines. PET consists of polymerized units of the monomer ethylene terephthalate, with repeating (C10H8O4) units and is commonly recycled.
15. Terephthalic acid and ethylene glycol undergo polyesterification to form PET.
a) True
b) False
View Answer
Explanation: Terephthalic acid and ethylene glycol undergo polyesterification to form PET. It is the most common thermoplastic polymer resin of the polyester family and is used in fibers for clothing, containers, etc.
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