Synthetic fibres and Plastics Class 8 Long type questions and Hots Questions
In this page we have synthetic fibres and Plastics Class 8 CBSE Important questions which includes long answer type questions and Hots questions.. Hope you like them and do not forget to like , social share
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Long answer type questions
What are blended fibres? Are they better than synthetic fibre? Explain with an example. Answers
Blended fibres are the fibres created by combining two different fibres so that they have the advantages of both. Generally, a synthetic fibre is added to a natural fibre.
e.g. Cotton blended with polyester (polycot) will give you the comfort of cotton along with the wrinkle- resistant of polyester so they are better than synthetic fibre and these are highly durable and last longer.
Why are plastics preferred these days? Explain giving example? Answers
Plastic are strong, lightweight, electrical insulators and resistant to chemicals and they are generally cheaper than metal so these properties make them highly versatile materials for making numerous household and industrial goods.
For e.g. Polythene, a thermoplastic is use widely as packaging material for liquid. Polystyrene is used for making electronic items.
1. Polyethylene terephthalate (PET) is used making containers that can be used in microwave ovens and bottles for packing mineral water and medicines. 2. Polyvinyl chloride (PVC) is used for making plumbing pipes, concealing electrical lining and furniture. 3. Bakelite is used for making electrical fitting.
What are biodegradable and non- biodegradable materials? Give one example of each of them? Answers
Biodegradable- A substance is biodegradable if it can be decomposed by the action of micro-organisms through a natural process. E.g. Paper, wood Non-biodegradable- Substances that cannot decay by natural process when acted upon by decomposers are called non- degradable substances. E.g. Plastic
How is rayon made? Why it is called artificial silk? Answers
Rayon is made from wood pulp. Wood pulp is first dissolved in an alkaline solution. The thick liquid produced is then passed through tiny holes to make fibres. The fibres are then hardened and spun into yarn and woven into clothes. It is called artificial silk because of its close resemblance to silk it has the shine of silk but costs much less than silk.
Name two polyester fabrics and their uses. Answers
Terylene and PET are two widely used polyester fabrics. Terylene is used to make very fine yarn by which various dress materials are made. PET is one of the familiar form of polyester that is used to make bottles, utensils, wires and many other things.
What are the common varieties of polyester? Also, mention the natural fibres, which are used for blending to enhance their properties. Answers
Polyester could be blended with natural fibres to enhance its properties. The common varieties of polyester are:
PET (Polyethylene terephthalate)
Terrycot: It is made by blending polyester and cotton.
Terrysilk: It is made by blending polyester and silk.
Terrywool: It is made by blending polyester and wool.
What are the disadvantage of synthetic fibres. Answers
a. Synthetic fibres cannot absorb moisture. This makes them unsuitable to be warm during summer because in summer when our body sweats. These fibres make body sticky and sometimes cause skin irritation.
b.They cannot be easily ironed as they melt very easily.
c.They are dangerous to be worn near fire or heat, as they easily catch fire and is unfit to be worm.
What is polymerization? Given below are two types of polymerization, identify it and describe them each.
the process of combining monomers to make a long chain or polymer is called polymerization.
Linear polymerization- when monomers are linked linearly it is linear polymerization.
Cross -linking polymerization- when monomers are cross-linked, it is cross – linking polymerization.
‘Plastics are hazard to environment’. Explain this statement. Answers
Yes, plastics are hazardous to environment. Plastics are non-biodegradable in nature.. If use of plastics were not reduced, our earth would turn into a big garbage bin.
The major problems due to plastics are:
If plastics are burnt, they release poisonous gases. which destroys the ozone layer of the earth and pollute the environment.
If the plastics are disposed in drains, they clog the drains causing waterlogging.
If animals swallow these plastics, they harm their digestive system, which leads to their death.
List down the characteristics of polyester. Answers
They are extremely strong and durable.
They are resistant to wrinkle, abrasion and most chemicals.
They are hydrophobic in nature. So, they can be easily washed and dried.
They are highly flammable so care should be taken while wearing them.
What is the difference between thermosetting and thermoplastics? Answers
What are the advantages of rayon? Answers
It is less expensive than silk.
It absorbs moisture and is comfortable to wear.
It blends well with other fibres particularly the woven ones.
It can be easily dyed to produce beautiful and vivid colors.
Feminine hygiene products and disposable diapers contain rayon.
Question 14 Study the image and answer the following question.
It clogs the drains, generate large amount of chemical pollutants, which harm the environment.
What is PET? What it is made up of? State its use. Answers
PET is a thermoplastic polymer, contains elements like carbon, hydrogen, and oxygen. It is used in making bottles for carbonated drinks, for acidic drinks, fruit juice. PET films are used as a base for recording tape.
ANSWER THE FOLLOWING QUESTIONS: (HOTS)
How can you show that thermoplastics are poor conductor of electricity from your daily life? Answers
all electric wires re insulated with plastics and those plastic covers do not cause any electric shock when touched.
A bucket made up of iron rusts but a bucket made up of plastic do not. Why? Answers
plastics do not react with water or air and hence are not rusted.
What kind of plastics are used to make these uniforms and why? Answers
these uniforms have a coating of melamine, which is a thermosetting plastic to make them flame resistant.
Why rayon is called “artificial silk”? Answers
It is less expensive alternative to silk fibre. Hence it is called artificial silk.
Rakesh went to a shop to buy blanket. The shopkeeper showed him two blanket one made of acrylic fibre and the other one of wool. He decided to buy acrylic blanket. Do you know why? Answers
Acrylic fabrics are durable, warm, less expensive, wrinkle resistant, strong, resistant to moths, retain shape.
Is nylon used for making parachutes? Justify your answer. Answers
yes, as it has high strength and good frictional resistance.
Why polybags should not be thrown in water bodies? Answers
As it clogs the drains and also harms the animals present inside it.
This synthetic fibres and Plastics Class 8 CBSE Important questions is prepared keeping in mind the latest syllabus of CBSE . This has been designed in a way to improve the academic performance of the students. If you find mistakes , please do provide the feedback on the mail.
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