Olympiad Test: Synthetic Fibres And Plastics - 2 - Class 8 MCQ

The polymer among the options is:
- Bakelite
- Polystyrene
- Polythene
Explanation:
- Bakelite is a type of polymer that is formed by the condensation polymerization of phenol and formaldehyde. It is a thermosetting plastic that is known for its electrical insulating properties and heat resistance.
- Polystyrene is a polymer that is made from the polymerization of styrene monomers. It is a versatile plastic that is commonly used in packaging materials, disposable cutlery, and insulation.
- Polythene, also known as polyethylene, is a polymer that is formed by the polymerization of ethylene monomers. It is a widely used plastic that has a range of applications, including packaging, construction, and manufacturing.
- Therefore, all of the given options (Bakelite, Polystyrene, and Polythene) are polymers.

Answer:
Introduction:
When a substance becomes soft on heating and can be molded into different shapes, it falls under the category of thermoplastic materials. These materials have the ability to soften upon heating and harden upon cooling, allowing them to be easily shaped and molded.
Explanation:
The substance mentioned in the question can be identified by understanding the properties of different thermoplastic materials.
Polythene:
- Polythene is a type of thermoplastic material that becomes soft and pliable on heating.
- It has a low melting point, allowing it to be easily molded into different shapes when heated.
- Polythene is commonly used for packaging materials, plastic bags, and various household items.
Rubber:
- Rubber is an elastomer, which means it has elastic properties even at room temperature.
- It does not become soft on heating, but rather retains its elasticity.
- Rubber is used in various applications such as tires, hoses, and seals.
Nylon:
- Nylon is a synthetic thermoplastic material that can be molded when heated.
- It has a high melting point, making it suitable for applications where heat resistance is required.
- Nylon is commonly used in textiles, automotive parts, and engineering components.
Rayon:
- Rayon is a semi-synthetic material made from cellulose fibers.
- It does not become soft on heating, but rather undergoes a chemical change when exposed to heat.
- Rayon is used in the textile industry for making clothing and other fabrics.
Conclusion:
Based on the given information, the substance that becomes soft on heating and can be molded into different shapes is polythene. Polythene is a thermoplastic material that is commonly used for packaging and household items.

Monomers are the basic unit of polymers.
Polymers are large molecules made up of repeating subunits called monomers. These monomers are the building blocks of polymers and are joined together through chemical reactions to form long chains or networks. Here is a detailed explanation of the relationship between monomers and polymers:
1. Definition of Monomers and Polymers:
- Monomers: Monomers are small, simple molecules that can join together to form larger, more complex molecules.
- Polymers: Polymers are macromolecules made up of repeating units of monomers.
2. Formation of Polymers:
- Monomers undergo a process called polymerization, where they combine with each other through chemical reactions.
- During polymerization, monomers form covalent bonds with one another, linking together to create long chains or networks.
- The repeating units of monomers in the polymer chain give the polymer its unique properties and characteristics.
3. Types of Polymers:
- There are two main types of polymers: addition polymers and condensation polymers.
- Addition polymers: These polymers are formed by the addition of monomers without the elimination of any byproducts. Examples include polyethylene and polystyrene.
- Condensation polymers: These polymers are formed by the elimination of small molecules, such as water or alcohol, during the polymerization process. Examples include nylon and polyester.
4. Importance of Monomers:
- Monomers are crucial for the formation of polymers as they provide the necessary building blocks.
- The choice of monomers determines the properties and characteristics of the resulting polymer.
- By varying the type and arrangement of monomers, different polymers with a wide range of properties can be synthesized.
In conclusion, monomers are the fundamental units that combine to form polymers. They play a vital role in determining the properties and behavior of the resulting polymer. Understanding the relationship between monomers and polymers is crucial in various fields, including chemistry, materials science, and biology.

Answer:
Introduction:
In order to determine which one of the following options is a fireproof plastic, we need to analyze the properties of each option and identify the one that best fits the description.
Properties of fireproof plastic:
A fireproof plastic is a material that does not burn or support combustion when exposed to fire. It is designed to resist high temperatures and prevent the spread of flames.
Analysis of options:
Let's analyze each option to determine if it matches the properties of a fireproof plastic.
1. Bad conductor of heat:
- While a bad conductor of heat may reduce the possibility of heat transfer, it does not necessarily mean that the material is fireproof.
- This option does not directly indicate resistance to fire or the ability to prevent the spread of flames.
2. Water soluble:
- Water solubility refers to the ability of a material to dissolve in water.
- It does not indicate fire resistance or the ability to withstand high temperatures.
- This option does not meet the criteria of a fireproof plastic.
3. Bad conductor of electricity:
- A material that is a bad conductor of electricity may have certain properties that contribute to fire resistance.
- However, this option does not directly indicate fireproof properties or the ability to withstand high temperatures.
4. Inflammable:
- Inflammable materials are highly flammable and can easily catch fire and burn.
- This option is the opposite of fireproof and does not meet the criteria.
Conclusion:
After analyzing all the options, it can be concluded that the correct answer is A: Bad conductor of heat. While this option does not explicitly indicate fireproof properties, it is the most plausible choice among the given options. It is important to note that fireproof plastics are specifically designed materials that undergo specialized treatments and contain certain additives to achieve fire resistance.

Correct Answer :- b

Explanation : Melamine is a versatile material. It resist fire and can tolerate heat better than other plastics. It is used for making floor tiles, kitchenware and fabrics which resist  fire.

Substitutes for glass of windows in cars:
There are several materials that can be used as substitutes for glass in car windows. One such material is Perspex, which is a brand name for acrylic plastic. Here is a detailed explanation of the options:
1. Fibre optic:
- Fibre optic is not a suitable substitute for glass in car windows.
- It is primarily used for transmitting light signals and does not provide the necessary strength and durability required for car windows.
2. Glass fibre:
- Glass fibre, also known as fiberglass, is not a direct substitute for glass in car windows.
- It is commonly used for reinforcing materials, such as in car bodies, but it is not transparent enough to be used in windows.
3. Teflon:
- Teflon, a brand name for polytetrafluoroethylene (PTFE), is not a suitable substitute for glass in car windows.
- While Teflon is known for its non-stick properties and resistance to heat and chemicals, it does not possess the clarity and transparency required for windows.
4. Perspex:
- Perspex, also known as acrylic or plexiglass, is a suitable substitute for glass in car windows.
- It is a transparent thermoplastic material that offers good visibility and impact resistance.
- Perspex is lightweight, shatterproof, and can be easily molded to fit the shape of car windows.
In conclusion, the correct answer is option D: Perspex, as it is a viable substitute for glass in car windows due to its transparency, impact resistance, and ease of molding.

Answer:
The strongest fiber on the basis of activity is Nylon.

• Nylon: Nylon is a synthetic fiber that is known for its strength and durability. It has a high tensile strength, meaning it can withstand a lot of pulling force without breaking. Nylon is commonly used in applications where strength is important, such as in ropes, fishing nets, and parachutes. It is also resistant to abrasion and chemicals, making it a suitable choice for various industrial uses.


• Polyester: Polyester is another synthetic fiber that is known for its strength. It has good tensile strength and is resistant to stretching and shrinking. Polyester is commonly used in clothing, upholstery, and industrial applications.


• Silk: Silk is a natural fiber that is known for its smoothness and luster. While silk is strong, it is not as strong as nylon or polyester. Silk is commonly used in luxury fabrics and textiles.


• Rayon: Rayon is a semi-synthetic fiber that is made from cellulose. It is not as strong as nylon or polyester and is more prone to stretching and wrinkling. Rayon is commonly used in clothing and home furnishings.

Therefore, on the basis of activity, the strongest fiber is Nylon.

To determine the monomer of polythene, let's analyze the options given:
A) Chlorine: Chlorine is an element and cannot be a monomer of polythene.
B) Methane: Methane is not a monomer of polythene. It is the simplest alkane and does not contribute to the structure of polythene.
C) Ethane: Ethane is a hydrocarbon with two carbon atoms. It is the monomer of polythene. Polythene, also known as polyethylene, is a polymer made up of repeating units of ethene (ethylene), which consists of two carbon atoms bonded together.
D) Iodine: Iodine is an element and cannot be a monomer of polythene.
Therefore, the correct answer is C) Ethane.

The fibre called artificial silk is Rayon.
Rayon is a synthetic fibre that is often referred to as artificial silk because of its similar appearance and texture to natural silk. It is made from regenerated cellulose, which is derived from wood pulp or other plant-based materials.
Here are some key points about Rayon as artificial silk:
1. Production: Rayon is produced through a process called the viscose process. In this process, cellulose is dissolved in a chemical solution and then extruded through fine holes to form filaments.
2. Similarities to Silk: Rayon closely resembles natural silk in terms of its softness, luster, and drape. It has a smooth and silky texture, making it a popular choice for clothing and textiles.
3. Advantages: Rayon is known for its excellent draping qualities, breathability, and moisture absorption. It is comfortable to wear, lightweight, and has good dyeability, allowing for vibrant colors.
4. Uses: Rayon is used in a wide range of applications, including clothing, home furnishings, and industrial products. It is commonly used in the production of dresses, blouses, shirts, linings, curtains, upholstery, and more.
5. Care: Rayon garments require special care as they can shrink or lose their shape when exposed to water or heat. It is advised to follow the care instructions provided by the manufacturer to maintain the quality and longevity of rayon clothing.
In conclusion, Rayon is often referred to as artificial silk due to its similar appearance and texture. It is a versatile and widely used synthetic fibre in the textile industry, offering a cost-effective alternative to natural silk.

The correct answer is C: Poly vinyl chloride.
Explanation:
Polyvinyl chloride (PVC) is a type of plastic that is widely used in various applications. Here is a detailed explanation of each option:
- A: Plastic very common in use: This option is incorrect as it does not provide the specific name or composition of the plastic.
- B: Plastic vinyl chloride: This option is partially correct as it includes the name "vinyl chloride," which is one of the components of PVC. However, it does not specify that PVC is a polymer.
- C: Poly vinyl chloride: This option is correct. PVC is a polymer composed of repeating vinyl chloride monomers. It is commonly used in construction, plumbing, electrical insulation, and many other applications.
- D: Polymer vinyl chloride: This option is incorrect as it does not provide the full name of PVC, which is polyvinyl chloride.
In conclusion, the correct answer is C: Poly vinyl chloride, as it accurately describes the composition of PVC.

To determine the liquid obtained when a paper strip is immersed in NaOH and then in carbon disulphide (Cs₂), we need to understand the reactions that occur with different types of materials.
When immersed in NaOH, the paper strip undergoes a reaction known as saponification. This reaction breaks down the ester bonds present in fatty acids of the paper, resulting in the formation of soap. The soap dissolves in water, forming a soapy solution.
Next, when the paper strip is immersed in carbon disulphide (Cs₂), it is used to extract any remaining organic compounds present. Carbon disulphide is a nonpolar solvent that can dissolve nonpolar substances.
Based on these reactions, we can determine the liquid obtained:
- Nylon: Nylon is a synthetic polymer that is not affected by NaOH or carbon disulphide. Therefore, the liquid obtained is not nylon.
- Viscose: Viscose, also known as rayon, is a semi-synthetic fiber made from cellulose. When immersed in NaOH, viscose dissolves and forms a viscous solution. When further immersed in carbon disulphide, viscose does not dissolve. Therefore, the liquid obtained is viscose.
- Plastic: Plastic is a broad term that encompasses a wide range of materials. However, most plastics are not soluble in NaOH or carbon disulphide. Therefore, the liquid obtained is not plastic.
- Cellulose: Cellulose is the main component of paper. When immersed in NaOH, cellulose undergoes saponification and forms a soapy solution. When further immersed in carbon disulphide, the remaining organic compounds are dissolved. Therefore, the liquid obtained is cellulose.
Therefore, the correct answer is B: Viscose.

Rayon and its Preparation
Rayon is a versatile fiber made from cellulose, a natural polymer found in plants. It is commonly used in textiles, medical supplies, and various industrial applications. The preparation of rayon involves several steps, including the use of specific solutions. NaOH and —— are two solutions commonly used in the preparation of rayon. Let's explore the options to identify the correct solution.
H₂SO₄
- Sulfuric acid (H₂SO₄) is not used in the preparation of rayon. It is a strong acid and can cause degradation of cellulose.
HCl
- Hydrochloric acid (HCl) is not used in the preparation of rayon. It is also a strong acid and can lead to the degradation of cellulose.
CO₂
- Carbon dioxide (CO₂) is not used in the preparation of rayon. It is a gas and does not play a role in the process.
C₁₂O₆H₁₂
- This compound, represented as C₁₂O₆H₁₂, is not relevant to the preparation of rayon. It does not have a direct involvement in the process.
Therefore, the correct answer is option A: NaOH. Sodium hydroxide (NaOH) is used as a solution in the preparation of rayon. It helps in the conversion of cellulose into a soluble form, which can then be spun into fibers to create rayon.
Overall, NaOH is a key solution in the preparation of rayon, while the other options mentioned (H₂SO₄, HCl, CO₂, C₁₂O₆H₁₂) are not involved in the process.

Answer:
The fibre used in the making of conveyor belts is Nylon. Here is a detailed explanation:
Nylon:
- Nylon is a synthetic fibre that is widely used in various industries due to its excellent properties.
- It is known for its high strength, durability, and abrasion resistance, making it an ideal choice for conveyor belts.
- Nylon fibres have a high tensile strength, which enables them to withstand heavy loads and constant motion without breaking or stretching.
- The low coefficient of friction of nylon helps in reducing the energy required for belt movement, resulting in improved efficiency.
- Nylon is resistant to chemicals, oils, and heat, making it suitable for applications in industries such as mining, manufacturing, and logistics.
- It is also resistant to moisture, which prevents the growth of mold or mildew on the conveyor belts.
- Additionally, nylon fibres have good flexibility, allowing the belts to bend and conform to different shapes and angles.
- The lightweight nature of nylon further enhances its suitability for conveyor belt applications, as it reduces the overall weight of the system.
In conclusion, nylon is the preferred fibre for making conveyor belts due to its strength, durability, abrasion resistance, and other favorable properties.

Answer:
The correct answer is B: Thermosetting plastic.
Explanation:
Here is a detailed explanation of why thermosetting plastic cannot be reheated to form new shapes:
1. Types of plastics:
- Plastics can be broadly classified into two types: thermoplastic and thermosetting.
- Thermoplastic: These plastics can be melted and reformed multiple times without undergoing any significant chemical change.
- Thermosetting: These plastics undergo a chemical change during the curing or hardening process and cannot be melted and reshaped after that.
2. Characteristics of thermosetting plastic:
- Thermosetting plastics are typically rigid and strong.
- They have a three-dimensional network structure due to the cross-linking of polymer chains during the curing process.
- Once cured, thermosetting plastics become permanently hard and cannot be softened or reshaped by heating.
- Heating thermosetting plastics beyond their curing temperature will result in decomposition rather than melting.
3. Examples of thermosetting plastics:
- Some common examples of thermosetting plastics are epoxy, phenolic, and melamine.
- These plastics are widely used in applications that require high strength, durability, and resistance to heat and chemicals.
4. Relevance to the question:
- Since thermosetting plastics cannot be reheated and reshaped, they do not have the ability to form new shapes once they have been cured.
- On the other hand, thermoplastic plastics can be reheated and reshaped multiple times, making them more suitable for recycling and reusing.
In conclusion, thermosetting plastics cannot be reheated to form new shapes, unlike thermoplastic plastics.

Answer:
The substance used in coating for making non-sticky utensils is Teflon. Here is a detailed explanation:
Teflon:
Teflon is a brand name for a type of non-stick coating made from a synthetic polymer called polytetrafluoroethylene (PTFE). It is known for its non-stick properties and is commonly used in cookware and kitchen utensils. Here are some key points about Teflon:
1. Non-stick properties: Teflon has a very low coefficient of friction, which means that it reduces the adhesion of food to the utensil's surface. This makes it easier to cook and clean, as food residues are less likely to stick to the utensil.
2. Heat resistance: Teflon is highly heat resistant, with a melting point of around 327 degrees Celsius (620 degrees Fahrenheit). This makes it suitable for use in cooking utensils, as it can withstand high temperatures without degrading or releasing harmful fumes.
3. Chemical resistance: Teflon is resistant to many chemicals, including acids and bases. This makes it durable and long-lasting, as it can withstand exposure to various substances without corroding or degrading.
4. Easy to clean: Due to its non-stick properties, Teflon-coated utensils are easy to clean. Food residues can be easily wiped off, and the utensils can be washed with mild soap and water.
5. Wide range of applications: Apart from cookware and utensils, Teflon is also used in various other applications, such as electrical insulation, automotive parts, and industrial coatings.
In conclusion, Teflon is the substance used in coating for making non-sticky utensils. Its non-stick properties, heat resistance, chemical resistance, and ease of cleaning make it a popular choice for cookware and kitchen utensils.