These AP 8th Class Physics Important Questions and 4th Lesson Synthetic Fibres and Plastics Class 8 Extra Questions will help students prepare well for the exams.
Class 8 Science Synthetic Fibres and Plastics Extra Questions
Synthetic Fibres and Plastics Class 8 Important Questions
Question 1.
What is polymer ?
Answer:
It is chain of small units, that join together to form a synthetic fibre.
Question 2.
Name some natural fibres.
Answer:
Cotton, wool, silk etc. are natural fibres.
Question 3.
Name some artificial fibres.
Answer:
Nylon, Terylene, Teflon, PET, acrylic etc., are artificial fibres.
Question 4.
What is cellulose ?
Answer:
Cellulose is a polymer made up of a large number of glucose units.
Question 5.
What is PET?
Answer:
PET is a form of polyester. It is a synthetic material used to manufacture bottles, wires, utensils, film etc.
Question 6.
Which raw material is used for making synthetic fibres ?
Answer:
All synthetic fibres are prepared from raw materials of petroleum origin called petrochemicals.
Question 7.
Cotton is a natural polymer. What is its chemical name ?
Answer:
Cellulose.
Question 8.
A synthetic fibre which looks like silk is obtained by chemical treatment of wood pulp. It is, therefore, known as artificial silk. What is its common name ?
Answer:
Rayon.
Question 9.
Terrycot is made by mixing two types of fibres. Write the name of the fibres.
Answer:
Terylene and cotton.
Question 10.
Name any two thermosetting plastics.
Answer:
Bakelite and melamine.
Question 11.
Name any two thermoplastics.
Answer:
Polythene and PVC (poly vinyl chloride)
Question 12.
Write two important properties of bakelite.
Answer:
- It is a poor conductor of electricity.
- It is heat resistant.
Question 13.
Why switches and plugs are made up of plastic ?
Answer:
Plastic is a poor conductor of heat and electricity.
Question 14.
Plastics articles are available in all possible shapes and sizes, can you tell why ?
Answer:
Plastic is easily moldable, so the articles can be made in any shape and size.
Question 15.
Plastic is used for making a large variety of articles of daily use and these articles are very attractive. But it is advised to avoid the use of plastics as far as possible. Why?
Answer:
Dut to its non-bio degradable nature it causes environmental pollution.
Question 16.
What is 5 R principle ?
Answer:
To get rid of heaps of garbage, everyone is advised to adopt 5 R principle : Reduce, Reuse, Recycle, Recover and Refuse.
Question 17.
Why is not advisable to burn plastic and synthetic fabrics ?
Answer:
Burning of plastic and synthetic fabrics produces lots of poisonous gases causing air pollution.
Question 18.
A bucket made of plastic does not rust like a bucket made of iron. Why ?
Answer:
Plastic is a non-reactive material. It does not react with air and water and does not rust.
Question 19.
Why does wearing nylon clothes are not preferable while cooking or working near a fire ?
Answer:
Nylon fibre easily catches fir. So it is not preferable to wear it while cooking, white working near a fire.
Question 20.
What is blending and what is the advantage of blending ?
Answer:
Any synthetic fibre can be combined with two or more other fibres is called blending. When two fibres are blended the resultant blended fibre possess the best qualities of both.
Question 21.
Which fibre source is not exhaustible ? Why ?
Answer:
Natural fibre source is not exhaustible because they are made from plants and animals, whereas artificial fibre are made from petrochemicals which are exhaustible.
Question 22.
What characteristics make rayon better than natural silk ?
Answer:
Rayon is cheaper and it can be dyed in different colours.
Question 23.
If you Want to purchase a door mat made of synthetic fibre, which synthetic fibre door mat will you select ? Why ?
Answer:
Nylon. It is durable, less in weight-and easy to wash. Rayon is cheaper and it can be dyed in different colours.
Synthetic Fibres and Plastics Extra Questions
Question 1.
What are the properties of nylon ?
Answer:
- Nylon is a synthetic fibrous material that is known for its high tensile strength, abrasion resistance and chemical stability.
- If is a very resistant fibre that is often used to make cords and ropes that need to support a lot of weight and withstand in wet, hot or dirty condition.
- When used in clothing, nylon is both light weight and warm.
Question 2.
Sagar took with him pylon ropes, when he was going for rock climbing. Can you tell why he selected nylon ropes instead of ropes made of cotton or jute ?
Answer:
Nylon ropes are strong, elastic and lighter as compared to cotton and jute ropes. A nylon thread is actually stronger than a steel wire.
Question 3.
Sudha went to the market to buy a blanket. The shop keeper showed her blankets made of acrylic fibers as well as made of wool. She preferred to buy and acrylic blanket. Can you guess, why ?
Answer:
Acrylic blankets are cheap, light in weight, more durable and are available in variety of colours and designs. They can be easily washed at home.
Question 4.
PVC is a theromplastic and is used for making toys, chappals etc. Bakelite is a thermosetting plastic and is used for making electrical switches, handles of various utensils, etc. Can you write the major difference between these two types of plastics?
Answer:
Thermoplastics get deformed easily on heating and can be bent easily on heating. On the other hand, thermosetting plastics when moulded once cannot be softened on heating.
Thermoplastics › Polythene and PVC
Thermosetting plastics › Bakelite and melamine
Question 5.
Why polyester is quite suitable for making dress materials ? Name any two types of polyesters and their uses.
Answer:
Fabric made from polyester does not get wrinkled easily. It remains crisp and is easy to wash. So, it is quite suitable for making dress material. You must have seen people wearing nice polyester shirts and other dresses. Terylene is a type of popular polyester. It can be drawn into very fine fibres that can be woven like any other yarn.
PET is a very familiar form of polyester. It is used for making bottles, utensils, films, wires and many other useful products.
Question 6.
By which material artificial wool is formed ? Why artificial wool has become more popular than natural wool ?
Answer:
Artificial wool is prepared from another type of synthetic fibre called acrylic. The wool obtained from natural sources is quite expensive whereas materials made from acrylic are relatively cheap. They are available in a variety of colours. Synthetic fibres are more durable and affordable which make them more popular than natural fibres.
Question 7.
Why is it advised not to wear synthetic clothes while working in a laboratory or working with fire in the kitchen ?
Answer:
The synthetic fibres melt on heating. This is actually a disadvantage with synthetic fibres. If the cloth catches fire it can be very disastrous. The fabric melts and sticks to the body of the person wearing it. It is therefore advised not to wear synthetic clothes while working in a laboratory or working with fire in the kitchen.
Question 8.
Write some properties and uses of melamine.
Answer:
Melamine is a versatile material. It resists fire and can tolerate heat better than Other plastics. It is used for making floor tiles, kitchenware and fabrics to resist fire.
Question 9.
List some characteristic properties of plastics.
Answer:
Some characteristic properties of plastics which make them useful are:
- Plastic is non-reactive
- Plastic is light, string and durable.
- Plastics are poor conductors.
Question 10.
Select the articles from the following list which are biodegradable,
a) paper
b) wool
c) plastic bag
d) woolen clothes
e) aluminium can
f) peels of vegetables
Answer:
(a), (b), (d) and (f).
Question 11.
Write two disadvantages of plastics.
Answer:
Since plastic takes several years to decompose, it is not environment friendly. It causes environmental pollution.
The polybags carelessly thrown here and there are responsible for clogging of the drains too.
Question 12.
Why are plastics considered to be a threat to our environment ?
Answer:
Plastics cannot be easily decomposed. When it is burnt to get rid of waste, it gives out poisonous gases and does not burn completely. They are non-biodegradable substances. Thus, plastics are considered a threat to our environment.
Question 13.
What are the advantages of natural fibre over artificial fibres ?
Answer:
When natural fibres, contribute to fabric it allows the skin to breath easily. Natural fibres are also generally free from irritating chemicals. Whenever fire accidents takes place they does not stick to the body.
Question 14.
Give example for popular polyester and what are its advantages ?
Answer:
The popular polyester is terylene.
- It can be drawn into very fine fabric fibres.
- Terylene is after mixed with cotton to form terricot with wool to give Teriwool. Which has best qualities of both blunded fibres.
Question 15.
What made the human beings to search for the alternative for natural fibres ?
Answer:
Human being is always going in search of new things which can make his life more comfortable and durable. As the natural fibres are not durable, elastic or light weight or lustrous or easy to wash, he needed and alternative to fulfill his.expectations. The solution to his expectations is synthetic fibre.
Question 16.
Imagine what would happen if we do not discover plastics.
Answer:
Now a days every object used in our day to day life is made of plastic. For example, milk and oil pouches, containers to store pickles and rice, buckets to store water, chains, water pipes, electrical appliances, television, radio and computers, mobile phones.
So plastic has taken over the place occupied by metal wood and glass items due to its special properties. So we cannot imagine our life without plastics because it is part of each and every aspect of life.
Question 17.
Which plastic is used in firemen’s uniform and why ?
Answer:
- Melamine plastic is used in firemen’s uniforms.
- Because, Melamine plastic is made of thermosetting plastic that is highly resistant to heat and fire. When exposed to high temperatures, it does not melt or drip.
Extra Questions of Synthetic Fibres and Plastics Class 8
Question 1.
Explain the difference between the thermoplastics and thermosetting plastics with help of a diagram* explaining in terms of arrangements of monomers.
Answer:
im
| Thermoplastics | Thermosetting plastics |
| Plastics which get deformed easily on heating and can be bent are known as thermoplastics Ex : PVC, polythene bags, toys, combs, etc. |
Plastics which moulded once can’t be softened by heating are called thermosetting plastics. Ex : Bakelite and melamine. |
Explanation :
- Thermoplastics have linear arrangement of monomers.
- But thermosetting plastics have cross linked arrangment.
- The difference in the arrangement of monomers bring the difference in their properties.
Question 2.
Write short notes on the following.
a) Plastic and healthcare industry, (b) Plastic cookware, (c) Teflon, (d) Fire proof plastic
Answer:
a) Plastic and health care industry : Plastics find extensive use in the health care industry. Some examples of their use in healthcare are the packing of tablets, threads used for stitching wounds, syringes, doctor’s gloves, a number of medical instruments etc.
b) Plastic cookware ; Plastic cookware is used in microwave ovens for cooking food. The heating process is different in microwave ovens. The heat cooks the food but does not affect the plastic vessel.
c) Teflon : Teflon is a non-stick plastic used as non-stick coating in cookwares. It is
also u$ed as tape for sealing purpose.
d) Fire proof plastics : Although synthetic fibres catchces fire easily, it is interesting to know that the fire proof material is made from synthetic plastics.
Question 3.
Classify the material as biodegradable and non-biodegradable.
1) Paper,
2) Wood,
3) Metals,
4) Cotton cloth,
5) Plastic container,
6) Woolen sweater,
7) Peels of vegetable; and fruit.
Answer:
| Material | Biodegradable/non-biodegradable |
| 1) Paper | Biodegradable |
| 2) Wood | Biodegradable |
| 3) Metals | Non-Biodegradable |
| 4) Cotton cloth | Biodegradable |
| 5) Plastic Container | Non-biodegradable |
| 6) Woolen Sweater | Biodegradable |
| 7) Peels of vegetable and fruit | Biodegradable |
Question 4.
Indicate whether the following statements are True or False. Also write the false statements iu their correct form.
a) The fabric terywool is obtained by mixing teryline and wool.
b) Synthetic fibres do not melt on heating.
c) It is risky to wear synthetic clothes while working in the kitchen.
d) Most of the plastics are biodegradable.
Answer:
a) True
b) False, Synthetic fibres melt on heating.
c) True
d) False, most of the plastics are non-biodegradable.
Question 5.
Write the importance of synthetic polymers in our life.
Answer:
The importance of synthetic polymers in our life are as follows.
Nylon : It is used for making ropes for climbing, fishing nets, rain coats, parachutes and tire cord etc.
Acrylic : Strong and warm, acrylic fibre is often used for sweaters, track suits, linings for boots and gloves and in furnishing fabrics and carpets.
Terylene : Terylene is intensively used in textile industry to make clothes like sarees, tapestry and dress materials. It is also mixed with natrual fibre like cotton and wool to make more variety of clothes.
Plastics : Plastics storing food item, water, milk, pickles, dry food etc. Plastic containers seem most convenient. This is because of light weight, low price, good strength and easy handling as compared to metals. Plastics are used in cars, aircrafts and space crafts.
Question 6.
Make some entries of Natural and artificial fibres.
Answer:
Natural and Artificial fibres
| Name of Article | Type of fibre (Natural/artificial) |
| 1. Cotton clothes | Natural |
| 2. Woolen clothes | Natural |
| 3. Silk clothes | Natural |
| 4. Nylon clothes | Synthetic |
| 5. Polyester clothes | Synthetic |
Question 7.
A material which gets decomposed through natural processes such as action by bacteria is called biodegradable. A material which is not easily decomposed by natural process is terned as non-biodegradable.
Since plastic takes several years to decompose. It is not environment friendly. It causes environmental pollution. Besides, the burning process in the synthetic material is quite slow and it does not get completely burnt easily. In the process, it releases lot of poisonous fumes into the atmosphere causing air pollution.
i) What is called biodegradable ?
Answer:
A material which gets a material which gets decomposed through a natural process such as action by bacteria is called biodegradable.
ii) What is non – biodegradable ?
Answer:
A material which is not easily decomposed by the natural process is called non- biodegradable.
iii) Is plastic biodegradable / non – biodegradable ?
Answer:
Plastic is non-biodegradable.
iv) Which causes environmental pollution ?
Answer:
Plastic causes environmental pollution.
v) Give example of biodegradable material.
Answer:
Wood, cow dung, paper, etc., are examples of biodegradable materials.