Polymer

1. With reference to polyethylene terephthalate, the use of which is so w

With reference to polyethylene terephthalate, the use of which is so widespread in our daily lives, consider the following statements:

  • 1. Its fibres can be blended with wool and cotton fibres to reinforce their properties.
  • 2. Containers made of it can be used to store any alcoholic beverage.
  • 3. Bottles made of it can be recycled into other products.
  • 4. Articles made of it can be easily disposed of by incineration without causing greenhouse gas emissions.

Which of the statements given above are correct ?

1 and 3
2 and 4
1 and 4
2 and 3
This question was previously asked in
UPSC IAS – 2022
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The correct statements are 1 and 3.
– Statement 1 is correct. PET fibres (polyester) are widely used in textile blends with natural fibres like cotton and wool to improve durability, wrinkle resistance, and other properties.
– Statement 3 is correct. PET bottles are one of the most commonly recycled plastic products, repurposed into various items including new bottles, textiles, and packaging materials.
– Statement 2 is incorrect. While PET containers are used for many beverages, including some lower-proof alcoholic ones like beer and wine, their suitability for *any* alcoholic beverage, especially high-proof spirits, is debated due to potential leaching of chemicals over time and potential degradation of the plastic itself. The statement is too broad.
– Statement 4 is incorrect. Incineration of PET releases carbon dioxide, a greenhouse gas. While modern incineration can capture energy, it still contributes to greenhouse gas emissions and can produce toxic substances if not performed under controlled conditions. Claiming no greenhouse gas emissions is false.
PET is a thermoplastic polymer resin. Its chemical name is polyethylene terephthalate. It is also known by the trade name Dacron (when used as fiber) and Mylar (when used as film). Its versatile properties make it suitable for packaging (bottles, food containers), textiles (polyester fabrics), films, and more.

2. Bisphenol A (BPA), a cause of concern, is a structural/key component i

Bisphenol A (BPA), a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?

Low-density polyethylene
Polycarbonate
Polyethylene terephthalate
Polyvinyl chloride
This question was previously asked in
UPSC IAS – 2021
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Bisphenol A (BPA) is a chemical compound used as a building block (monomer) primarily in the production of polycarbonate plastics and epoxy resins. Polycarbonate is a strong, transparent, and durable thermoplastic polymer used in various products, including some food containers, water bottles, baby bottles (now restricted in many places), CDs, DVDs, and eyeglasses. While BPA use is being reduced or banned in certain applications due to health concerns, it remains a key component in manufacturing polycarbonate.
– Bisphenol A (BPA) is an industrial chemical.
– It is a key structural component in the manufacture of polycarbonate plastic and epoxy resins.
– Polycarbonate is used in various consumer products.
Concerns about BPA stem from its potential to leach into food and beverages from containers and its classification as an endocrine disruptor, meaning it can interfere with hormonal systems. Many products are now marketed as “BPA-free,” indicating the use of alternative materials or manufacturing processes. LDPE, PET, and PVC are different types of plastics manufactured using different monomers and processes, and do not typically contain BPA.

3. Which one of the following is not a condensation polymer?

Which one of the following is not a condensation polymer?

Nylon
DNA
Polythene
Bakelite
This question was previously asked in
UPSC CAPF – 2018
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Polythene (polyethylene) is formed by the addition polymerization of ethylene monomers (CH2=CH2). In addition polymerization, monomers add to one another without the elimination of any small molecules. Condensation polymerization, on the other hand, involves the reaction between monomers with the elimination of a small molecule such as water (H2O), alcohol, or ammonia.
Condensation polymers are formed with the elimination of a small molecule during polymerization. Addition polymers are formed by the simple addition of monomers without any elimination.
Nylon is a polyamide formed by the condensation reaction between a diamine and a dicarboxylic acid (or between amino acids). Bakelite is a phenol-formaldehyde resin formed by condensation. DNA is a biopolymer where nucleotides are linked by phosphodiester bonds, the formation of which involves the elimination of water (a condensation-like process), but in the context of synthetic polymers, Polythene is the clear example of an addition polymer among the options, making it the one that is *not* a condensation polymer.

4. Match List-I with List-II and select the correct answer using the code

Match List-I with List-II and select the correct answer using the code given below the Lists :

List-I
(Compound)		 List-II
(Type of polymer)
A. Melamine 1. Linear
B. Polyvinyl chloride 2. Condensation
C. Terylene 3. Natural
D. Cellulose 4. Cross-linked

Code :

A-3, B-2, C-1, D-4
A-4, B-1, C-2, D-3
A-3, B-1, C-2, D-4
A-4, B-2, C-1, D-3
This question was previously asked in
UPSC CAPF – 2018
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The correct matching is A-4, B-1, C-2, D-3.
– **Melamine:** Melamine-formaldehyde resin is a thermosetting polymer formed by condensation polymerization, resulting in a rigid, **cross-linked** structure.
– **Polyvinyl chloride (PVC):** Formed from vinyl chloride monomers (CH2=CHCl) via addition polymerization. PVC chains are essentially **linear**.
– **Terylene (PET):** Polyethylene terephthalate is a polyester formed by **condensation** polymerization of ethylene glycol and terephthalic acid.
– **Cellulose:** A naturally occurring polysaccharide found in plant cell walls. It is a **natural** polymer.
Polymers can be classified based on their structure (linear, branched, cross-linked), origin (natural, synthetic), and synthesis method (addition, condensation). Melamine is known for its use in laminates and molded plastics due to its cross-linked structure. PVC is a common thermoplastic used in pipes, cables, etc. Terylene is widely used as a fiber (polyester fabrics) and in bottles. Cellulose is the main component of wood and cotton.

5. In most of the children’s toys, a toxic chemical remains present. In t

In most of the children’s toys, a toxic chemical remains present. In this respect, which among the following statements is/are correct?

  • 1. The name of the toxic element is phthalates which are esters of phthalic acid.
  • 2. They are mainly used as plasticizers, i.e., substances added to plastics to increase their flexibility and longevity.
  • 3. They are easily released into environment because there is no covalent bond between the phthalates and plastics in which they are mixed.

Select the correct answer using the code given below.

1 only
2 only
Both 1 and 2
Neither 1 nor 2
This question was previously asked in
UPSC CAPF – 2012
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Based on the provided options which only evaluate statements 1 and 2, the correct option is C, stating that both 1 and 2 are correct.
The question refers to a toxic chemical commonly found in children’s toys, known as phthalates. Phthalates are used to make plastics more flexible and durable.
Statement 1: The toxic elements often found in plastics, especially in toys, are phthalates, which are esters of phthalic acid. This statement is correct.
Statement 2: Phthalates are primarily used as plasticizers, substances added to plastics to increase their flexibility, transparency, durability, and longevity. This statement is correct.
Statement 3: Phthalates are not covalently bonded to the plastic polymer matrix; they are mixed into the plastic. This allows them to leach out or be released into the environment (including into a child’s mouth if the toy is chewed). This statement is also correct.
However, the provided options A, B, C, D only offer combinations involving statements 1 and 2. Evaluating only statements 1 and 2 against these options: Statement 1 is correct, and Statement 2 is correct. Therefore, “Both 1 and 2” is the correct option among the choices given.

6. Which one of the following is used as a binder in paints ?

Which one of the following is used as a binder in paints ?

Titanium dioxide
Novolac
Phthalocyanine
Silicones
This question was previously asked in
UPSC NDA-1 – 2019
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Novolac is used as a binder in paints.
In paint formulation, a binder (also known as the vehicle) is the component that forms a film to hold the pigment particles together and adhere them to the surface being painted. Titanium dioxide and Phthalocyanine are examples of pigments, which provide color and opacity. Silicones are polymers that can be used in paints, often as additives for properties like water repellency or flexibility, or as binders in specialized coatings, but Novolac (a type of phenolic resin) is a well-established binder, particularly used in durable coatings like primers, can coatings, and industrial finishes due to its excellent chemical resistance and hardness.
Common binders in paints include acrylics, alkyds, epoxies, polyurethanes, and phenolic resins like Novolac. The choice of binder significantly impacts the paint’s properties, such as durability, adhesion, gloss, drying time, and resistance to chemicals and weather. Pigments like titanium dioxide (white) and phthalocyanines (blue/green) provide color and opacity but do not bind the paint components together.

7. Which one of the following compounds is used for the synthesis of

Which one of the following compounds is used for the synthesis of silicones?

SiCl₄
(CH₃)₂Si(OH)₂
SiO₂
Na₄SiO₄
This question was previously asked in
UPSC Geoscientist – 2023
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The correct answer is (CH₃)₂Si(OH)₂.
Silicones are polymeric organosilicon compounds. They are typically synthesized by the hydrolysis of alkyl or aryl substituted chlorosilanes, such as R₂SiCl₂. The hydrolysis of (CH₃)₂SiCl₂ yields (CH₃)₂Si(OH)₂, which is a silanol. These silanol monomers then undergo condensation polymerization by eliminating water molecules between hydroxyl groups, forming Si-O-Si linkages, which constitute the backbone of silicones.
While chlorosilanes like R₂SiCl₂ are the starting materials for the synthesis of linear silicones, the hydrolysis product, R₂Si(OH)₂, is the intermediate that directly undergoes polymerization. SiCl₄ can be used to produce branched or cross-linked silicones (by yielding Si(OH)₄ upon hydrolysis, which can polymerize in multiple directions), but the simple linear silicones often start from dialkyl dichlorosilanes and their hydrolysis products. SiO₂ (silica) is a natural inorganic compound, not used as a direct monomer for common silicones synthesis. Na₄SiO₄ is sodium orthosilicate, which is a silicate salt, also not a typical monomer for silicone synthesis.

8. Which one of the following polymers does not contain glucose units?

Which one of the following polymers does not contain glucose units?

Glycogen
Starch
Cellulose
Rubber
This question was previously asked in
UPSC CDS-2 – 2017
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The correct answer is Rubber.
Glycogen, Starch, and Cellulose are all polysaccharides, which are complex carbohydrates. They are polymers made up of repeating units of glucose (a monosaccharide). Glycogen is the storage form of glucose in animals and fungi. Starch is the storage form of glucose in plants. Cellulose is a major structural component of plant cell walls. Natural rubber is a polymer of isoprene (2-methyl-1,3-butadiene), which is an organic compound belonging to the diene class.
While glycogen, starch, and cellulose are polymers of glucose, they differ in the type of glycosidic bonds connecting the glucose units and their branching structures, which gives them different properties and functions. Rubber’s monomer unit is chemically distinct from glucose.

9. When hot water is placed into an empty water bottle, the bottle keeps

When hot water is placed into an empty water bottle, the bottle keeps its shape and does not soften. What type of plastic is the water bottle made from?

Thermoplastic
PVC
Polyurethane
Thermosetting
This question was previously asked in
UPSC CDS-1 – 2019
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The question describes a water bottle that retains its shape and does not soften when hot water is placed in it. This property is characteristic of thermosetting plastics. Thermoplastics soften upon heating and can be reshaped, which is why typical PET water bottles deform when exposed to hot liquids. Thermosetting plastics undergo irreversible chemical cross-linking during their formation and remain rigid when heated; they will eventually decompose or char at very high temperatures but do not soften.
– Thermoplastics soften and become pliable upon heating.
– Thermosetting plastics remain rigid upon heating.
– The bottle not softening with hot water indicates it is not a thermoplastic.
Common water bottles are made from PET, a thermoplastic. However, if a bottle is designed to withstand hot water without softening, it is likely made from a thermosetting plastic or a specialized high-temperature thermoplastic, but given the options and the definitive statement “does not soften”, thermosetting is the most fitting category. PVC is a thermoplastic, and while some polyurethanes can be rigid, the description points towards the general class of thermosets.

10. The monomer/monomers used for the synthesis of Nylon 6 is/are

The monomer/monomers used for the synthesis of Nylon 6 is/are

hexamethylenediamine and adipic acid
caprolactam
urea and formaldehyde
phenol and formaldehyde
This question was previously asked in
UPSC CDS-1 – 2019
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The correct option is B.
Nylon 6 is synthesized through the ring-opening polymerization of caprolactam. Caprolactam is a cyclic amide (lactam) with six carbon atoms. Upon heating, the ring opens, and the linear molecules polymerize.
Option A, hexamethylenediamine and adipic acid, are the monomers for Nylon 6,6, which is formed by condensation polymerization. Option C, urea and formaldehyde, react to form urea-formaldehyde resin. Option D, phenol and formaldehyde, react to form phenol-formaldehyde resin (Bakelite).
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