Science In Everyday Life Solutions for Class 8 Science Chapter 3 Synthetic Fibres And Plastics are provided here with simple step-by-step explanations. These solutions for Synthetic Fibres And Plastics are extremely popular among class 8 students for Science Synthetic Fibres And Plastics Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Science In Everyday Life Book of class 8 Science Chapter 3 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Science In Everyday Life Solutions. All Science In Everyday Life Solutions for class 8 Science are prepared by experts and are 100% accurate.

Page No 52:

Question 1:

What are synthetic fibres? Give two examples.

Answer:

The fibres which are produced chemically by human beings are called as synthetic fibres. Most of the synthetic fibres are obtained from coal, petroleum and natural gas. Nylon and rayon are two examples of synthetic fibres.

Page No 52:

Question 2:

Give two uses each of rayon, polyester, and spandex.

Answer:

The uses of synthetic fibres are ,
(i) Rayon : Because of its lustrous nature, rayon is used in making shirts, ties and home furnishings.
(ii) Polyester : Though polyester is light weight, it is strong and has a good elasticity. Thus, it is used in making magnetic recording tapes in audio cassettes and in making of conveyor belts.
(iii) Spandex : Because of its excellent elasticity, spandex is used in making swim suits, T- shirts and caps.

Page No 52:

Question 3:

What are the properties and uses of nylon?

Answer:

Nylon is highly elastic, lustrous and easy to wash. Due to these properties,
(i) Nylon is used in making sarees, stocks, umbrellas.
(ii) Toothbrush bristles are made of nylon fibres.
(iii) Nylon threads are used in making fishing nets and climbing ropes, because of their strength and elasticity.

Page No 52:

Question 4:

Plastics are poor conductors of heat. What does this property of plastics make them suitable for?

Answer:

Plastics are poor conductors of heat. This property of plastics is used in making the handles of cooking vessels, containers for microwave oven and in refrigerators.

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Question 5:

What do the following stand for: PP, HDPE, PS, and PET? Write two uses of each.

Answer:

 Type of the plastic Uses
PP - Poly-Propylne  Used in the manufacture of ketchup bottles and automobile battery castings.
HDPE - High Density Poly Ethylene. Used in the manufacture of corrosive chemicals like bleaches and acids.
PS - Poly Styrene Used in the manufacture of thermocol which is used for making disposable cups and packaging material.
PET - Poly ethylene Terepthalate Used in the manufacture of containers for microwave cooking and bottles of carbonated beverages.

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Question 6:

Suggest ways of countering the harmful effects associated with plastic disposal.

Answer:

The two ways of countering the harmful effects associated with plastic disposal are
(i) Reducing the usage of plastics
(ii) Recycling and reusing of plastics.

Page No 52:

Question 1:

What are the advantages and disadvantages of synthetic fibres?

Answer:

Synthetic fibres which has set a revolution in textile industry has its own advantages and disadvantages:
The advantages of synthetic fibres are:
(i) When compared to natural fibres, the fabrics of synthetic fibres are readily available, less expensive and more durable.
(ii) The synthetic fibres have good elasticity and the fabrics of these fibres do not wrinkle easily.
(iii) Because of their elasticity and durability, they can handle heavy loads without breaking.
The disadvantages of synthetic fibres are:
(i) Since, they melt easily, special care is to be taken while ironing the fabrics.
(ii) Most of the fabrics of synthetic fibres becomes sticky on absorption of little moisture, which makes them unfit to wear during summer.
(iii) It is very dangerous to go near the fire source wearing a fabric of synthetic fibre as it may catch fire quickly.

Page No 52:

Question 2:

What are the main differences between thermoplastics and thermosetting plastics? Give one example of each.

Answer:

 Thermoplastics  Thermosetting plastics
 It is a class of plastics in which the individual units may be linear or lightly cross linked. It is a class of plastics in which the individual units undergo heavy crossing after shaping.
Melts on heating which can be remoulded into desired shapes, which can be reversed. Once shaped, cannot be remoulded after reheating.
Examples include Poly vinyl Chloride. Examples include melamine.

Page No 52:

Question 1:

Write one word for the following.

1. A synthetic fibre also called artificial silk ....................
2. The first true synthetic fibre ....................
3. The most commonly used polyester ....................
4. A synthetic fibre that closely resembles wool ....................
5. A synthetic fibre also known as Lycra ....................

Answer:

1. Rayon

2. Nylon

3. Terylene

4. Acrylic

5. Spandex

Page No 52:

Question 1:

Which of the following is a synthetic fibre?
(a) Wool
(b) Cotton
(c) Nylon
(d) Silk

Answer:

(c) Nylon.
Nylon is a synthetic fibre.

Page No 52:

Question 2:

Which of the following is used for making lightweight sails?
(a) Polyester
(b) Nylon
(c) Rayon
(d) Polystyrene

Answer:

(a) Polyester
Polyester is used for making lightweight sails.

Page No 52:

Question 3:

Which of the following type of plastic is used for making microwave cooking containers?
(a) HDPE
(b) PS
(c) PP
(d) PET

Answer:

(d) PET
PET is used for making microwave cooking containers.

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Question 4:

Which of the following is used for making grocery bags?
(a) PP
(b) PS
(c) LDPE
(d) PET

Answer:

(c) LDPE
LDPE is used for making grocery bags.

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Question 5:

Which of the following is not a property of plastics?
(a) Inflammable
(b) Corrode and rust easily
(c) Poor conductors of electricity
(d) Insoluble in water

Answer:

(b) Corrode and rust easily
Plastics does not corrode and rusts easily.

Page No 52:

Question 1:

Fill in the blanks with the correct words.
1. Fibres that are made by human beings are called .................... (natural/synthetic) fibres.
2. .................... (Polyester/Rayon) absorbs sweat.
3. .................... (Nylon/Rayon) are used for making toothbrush bristles.
4. .................... (Spandex/Nylon) has excellent elasticity.
5. Most synthetic fibres .................... (can/cannot) handle heavy loads without breaking.

Answer:

1. Fibres that are made by human beings are called synthetic fibres.
2. Rayon absorbs sweat.
3. Nylon are used for making toothbrush bristles.
4. Spandex has excellent elasticity.
5. Most synthetic fibres can handle heavy loads without breaking.



Page No 53:

Question 3:

Describe the general properties of plastics.

Answer:

The general properties of plastics are as follows:
(i) Plastics are bad conductors of heat. Thus, they are used in making the handles of cooking vessels, containers for microwave oven and in refrigerators.
(ii) Plastics are bad conductors of electricity and used as covering materials in electrical appliances, wires, cords etc.
(iii) Plastics are insoluble in water, they are used for making containers to store water such as cans, vessels, bottles etc.
(iv) Plastics are non-reactive to acids and other salts as they do not corrode or rust. Therefore, they are used to store chemicals.
(v) Plastics are inflammable, plastics melt down quickly when kept near a source of fire.

Page No 53:

Question 4:

Explain the harmful effects associated with the disposal of plastics.

Answer:

Plastics are non biodegradable wastes. Disposing plastic wastes into the environment causes adverse effects on the living beings. Some of the harmful effects associated with the disposal of plastics are:
(i) Plastics disposed into the environment clot under the soil as they don't easily degrade, avoiding the rainwater getting absorbed by the soil. This cause harm to the plants as they do not get sufficient water for their growth.
(ii) Burning of plastics produces harmful smoke and vapours, which causes respiratory ailments and other disorders in living beings.
(iii) Disposal of plastics into water sources causes the harm to the aquatic life. The toxic material present in the plastics can cause reproductive failure in fish and may even lead to death of the aquatic animals.

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Question 5:

List a few things that can be done to limit the harmful effects associated with plastics.

Answer:

The harmful effects associated with the disposal of plastics can be reduced by following some simple tips. They are:
(i) Segregating biodegradable and non biodegradable wastes in separate garbage bins helps to keep the environment clean, as it helps in proper disposal of this waste.
(ii) Carrying cloth bags or paper bags while going for shopping reduces the number of plastic bags and thereby reduces the accumulation of plastic in nature.
(iii) Once used plastic bags should not be thrown out, instead, it can be reused or can be collected for recycling.



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