CBSE Class 8 Science Synthetic Fibers And Plastics Worksheet

A. Multiple choice questions:

Question. Which of the following fibres gives wool-like feeling?
(a) nylon
(b) acrylic
(c) terylene
(d)rayon
Answer. b- acrylic

Question. Which of the following is not a thermoplastic?
(a) polythene
(b) melamine
(c) polyester
(d) PVC
Answer. b-melamine

Question. Which of the following is used for making water pipes?
(a) melamine
(b) polythene
(c) PVC
(d) Bakelite
Answer. c-PVC

Question. Terylene mixed with cotton from_____________.
(a) terrycot
(b) terrywool
(c) terrysilk
(d) polyester
Answer. a-terrycot

B. FILL IN THE BLANKS-
1.Synthetic fibres absorb very little water. This property is called ______.
2. Thermosetting plastic does not become _______ on heating.
3. Plastic wastes dumped in water cause _______
4. _______ is a common plastic known for its lightness and rigidity.
Answer.
1. Drip dry              2. Soft
3. Water pollution   4. Thermocol

C. VERY SHORT ANSWER QUESTION-

Question. Name the smallest unit of nylon.
Answer. The smallest unit of nylon is amide.

Question. Give any two examples of thermoplastics.
Answer. The two examples of thermoplastics are-
1. PVC 2. Polythene

Question. Give two examples to show that plastics are non-reactive in nature.
Answer. (a.) Plastics are non-reactive with water. That is why plastic containers such as bottles and buckets are used to store water.
(b.)Plastics are non reactive so pickles are stored in them.

Question. Which fibre is also called artificial silk?
Answer. Rayon is also called artificial silk.

Question. Name the monomer of polyester.
Answer. The monomer of polyester is ester.

Question. Give two examples of plastics.
Answer. The two examples of plastics are-
(a) Bakelite (b) Polythene

D. SHORT ANSWER QUESTIONS-

Question. What are human-made or synthetic fibres?
Answer. Fibres obtained through different chemical processes in the industries are called human-made or synthetic fibres. Rayon, nylon and terylene are some human-made or synthetic fibres.

Question. What is a polymer?
Answer. A polymer is a very large unit formed by the combination of a large number of smaller molecules (called monomers) joined end to end by chemical bonds.

Question. Why is nylon used for making bristles of toothbrushes?
Answer. Due to its high tensile strength, nylon is used for making bristles of toothbrushes.

Question. What is 5-R principal?
Answer. In order to save environment from harmful effects of plastic, we should use 5R principal-reduce, reuse, recycle, recover and refuse.
(a) Reduce- It means that we should use less like save water by repairing leaky taps.
(b) Reuse- It means to use an item again after it has been used.
(c) Recycle-This means we should collect items like plastic ,paper, and glass use materials to make new products, instead of using new plastic.
(d) Recover- It means converting waste into resources .
(e) Refuse- We can refuse to use products which are harmful to the environment.

Question. (a). What are plastics?
Answer. Plastics are polymers made up of a very large number of small units joined end to end to form long chains.

(b). Give any two uses of plastics.
Answer. 1. Plastics are used to store various kinds of food material and many chemicals.
2 Plastics are used to make buckets, tubs, and most of our household articles.

Question. Give the difference between thermosetting plastics and thermoplastics.
Answer.
THERMOPLASTIC                                                                   THERMOSETTING PLASTICS
Plastics that easily get deformed                                            Plastics that once moulded into a shape do not
on heating and can be bent easily                                          become soft on heating and cannot be moulded again.
They are less tough as compared to thermosetting plastics. They are more tough and rigid.
They are less resistance to high temperatures.                     They are resistance to high temperature.
They can be recycled.                                                           They cannot be recycled.
Examples- PVC, Polyesters                                                   Examples- Bakelite, Formica

Question. (a) Why is polyester used for making water hoses for firefighting operations?
Answer. Polyester is strong and resistant to chemicals and abrasion that’s why it is used for making water hoses for firefighting operations.

(b) Why are saucerpan handles, electric plugs and switches made of thermosetting plastics?
Answer. Thermosetting plastics are bad conductor of electricity i.e. they donot allow electricity to pass through them so they are used to make saucerpan handles, elecrtric plugs and switches.

E. LONG ANSWER QUESTIONS-

Question. Give any five environmental hazards caused due to plastics.
Answer. Five environmental hazards caused due to plastics are-
1. Plastics are not at all ecofriendly. Some plastics can be recycled but recycled plastics are inferior in quality.
2. Plastics burn slowly and release toxic fumes.
3. Plastics are nonbiodegradable and keep accumulating in landfills.
4. Plastics and polythene bags choke the drains and create a lot of drainage problems. This also leads to eutrophication causing harm to aquatic life.
5. Inferior quality plastics prove to be hazardous if used in food packing or eatables.

Question. What are the advantages of synthetic fibres? Explain.
Answer. The advantage of synthetic fibres are-
(a) Synthetic fibres can be produced on a large scale and, hence, they cost less.
(b) These fibres are strong, durable and shiny.
(c) These fibres require less care and do not need frequent ironing as they are wrinkle free.
(d) The manufacture of fully synthetics fibres is helping in the conservation of forest.

Question. Write any five eco-friendly habits.
Answer. Five eco-friendly habits are-
1. Limit the use of plastics.
2. Use paper or cloth bags instead of polythene.
3. Do not throw plastics or polythene into water bodies.
4. Do not burn plastics.
5. Avoid wearing synthetic clothes in kitchen.

Question. Give reasons for the following-

1. Cooking pans have plastics handles.
Answer. Cooking pans have plastics handles because they do not conduct heat and are good insulators of heat.

2 Burning of plastics causes air pollution.
Answer. Plastics do not get completely burnt and produce toxic gases and smoke that causes air pollution.

3 Electric wires have a plastics covering.
Answer. The electric wires are covered with plastics as they are insulators or bad conductor of electricity. They are used for the safety as they prevent electric shock.

4 Plastics are strong and durable.
Answer. Plastics are strong and durable as they can be moulded into different shapes and sizes.

More Question

Fill up the blanks :

1. Fibres we get from plant and animals are called ______________.
2. Artificial fibres are commonly called _________________.
3. The simple molecule of molecule in a polymer is called _____________.
4. The polymer of natural fibre cotton is called ______________.
5. The material which can easily be molded is called ________________.
6. The process by which artificial fibres are made from simple fibre is called _______________.
7. The raw material used for the production of rayon is ______________.
8. ________________ is made by the polymerisatin of amide molecules.
9. Terylene is obtained by the polymerising the molecule of ___________ and _________________.
10. Acrylic fibre is obtained by the polymerisation of molecules of _________________.
11. Koroseal is the trade name of ________________.
12. PVC stands for ________________.
13. PET stands for __________________.
14. _________________ prepared by the polymerization of vinyl chloride molecules.
15. Two examples of thermoplastic.

MICROORGANISMS: FRIEND AND FOE

Q1. Answer the following:

i. Microbes that reproduce only inside the hostii.

ii. A viral diseaseiii.

iii. An example of a fungiiv.

iv. Single celled microbesv.

v. Microorganism that increases soil fertilityvi.

vi. Microbes that could be present in form of coloniesvii.

vii. Bacteria which causes anthrax diseaseviii.

viii. Any one preservativeix.

ix. A plant that can show root nodule formation –

x. A useful Fungixi.

xi. A disease that has been eradicated from most parts of the world –

xii. A bacterial disease in plants-

Q2. Tick the correct option:

1. Microbe involved in curd formation:
i) Amoeba
ii) Lactobacillus
iii) Rhizobium
iv) Bread Mould

2. Which of the following is not a fungi:
i) Bread Mould
ii) Penicillium
iii) Aspergillus
iv) Spirogyra

3. The carrier of malarial parasite:
i) Anopheles
ii) Aedes
iii) Housefly
iv) Virus

4. Rust of wheat is caused by:
i) Bacteria
ii) Virus
iii) Fungi
iv) Protozoa

5. Which of the following can result in spread of microbes:
i) Air
ii) Water
iii) Food
iv) All of these

6. The term vaccine was introduced by which scientist?
i) Edward Jenner
ii) Robert Hooke
iii) Alexander Flemming
iv) Robert Koch

7. Chlorophyll is present in which of the following organisms
i) Bacteria
ii) Virus
iii) Algae
iv) Protozoa

8. Yeast is used in the production of:
i) Hydrochloric acid
ii) Alcohol
iii) Sugar
iv) Oxygen

9. Which of the following does not contribute to nitrogen availability in the soil?
i) Decay of organic matter
ii) Lightning
iii) Rhizobium
iv) Lactobacillus

Q3. Give the contributions of the following:
A. Louis Pasteur
B. Alexander Fleming
C. Robert Koch

Q4. Name some antibiotics obtained from microbes?

Q5. Define:
A. Microbes
B. Pathogens
C. Nitrogen Fixation
D. Pasteurization
E. Preservatives
F. Carriers

Q6. Give two uses of microorganisms in the following areas:
i) Food Industry
ii) Medicinal Use
iii) Environment related

Q7. Why milk in polypacks does not get spoiled?

Q8. List few differences between Antibiotics and Antibodies?

Q9. List some harmful effects of microorganism?

Q10. How can we control the spread of diseases caused by mosquitoes?

Q11.Why does sugar solution with yeast powder become alcoholic in taste?

Q12. Megha, a class VIII student was asked to submit a project report on mosquito transmitted diseases. She visited a nearby hospital where her aunt was staffed as a nurse. Her aunt took her to a patient suffering from malaria. Megha talked to the patient and asked him about his health and also took some flowers for him.
(a) Name the mosquito that spreads malaria.
(b) What is the name given to such organisms that transmit the diseases from infected to healthy persons?
(c) How can we control the spread of diseases by mosquitoes?
(d) Identify two important values as shown by Megha.

Q13. Kushal's family is happy as he became a proud father to a baby girl. Upon a routine visit to the hospital, the doctor advised him not to skip the vaccination schedule. While discussing the same at home, one of the family members suggested that vaccination is not necessary for a girl child. Kushal opposed this suggestion.
(a) What is vaccination?
(b) Name the scientist who prepared the first vaccine?
(c) Critically comment upon Kushal's viewpoint.

Q14. Fill ups:

1. Tuberculosis is caused by _________________________.

2. Tetanus disease is caused by _____________________.

3. ____________________ fixes atmospheric nitrogen useful to plants.

4. ______________ is used in production of vinegar from alcohol.

5. A micro-organism that has no cellular structure.____________.

6. Fungi used in bakeries._________________ .

7. Microbes lying on the border of living and non-living._______________ .

Q15. Name 2 bacterial diseases that spread through the medium of
a) AIR: __________________, _______________________
b) Contaminated food and water :____________________,_______________________

1. Write one use of following fibres.

a) Rayon ________________________________________

b) Nylon ________________________________________

c) Polyester ________________________________________

d) Acrylic ________________________________________

2. What are 3R stands for ___________ ___________ ___________

3. Complete the following bable --
Item                                                        Thermoplastic / Thermosetting
Toys
Electrical switch
Handles of utensils
Comb
Kitchen ware (crockery)
Bucket
Floor Tiles
Telephone Instruments

4. Categorise the following things according to the type of fibre from which they are made as natural / man made

Woolen clothes _______________ Paper _______________

Silk Saree _______________         Nylon Socks _______________

Tooth Brush _______________       Cotton Clothes _______________

5. Paste the sample of cloth made up of type of fibre as mentioned below.

Q1. Fill in the blanks:-

1. Clothes are made up of ______________ which are made from __________.

2. The polymer cellulose is made up of a large number of ________________ units.

3. Silk fibre is obtained from _____________ whereas artificial silk is obtained by chemical treatment of _______________.

4. The polymer polyester is made up of repeating units of ______________.

5. Synthetic fabrics soak _____________ water than the natural fabrics and take ______________ time to dry.(less/more)

6. Polythene which is used to make polythene bags is an example of a ________.

7. Iron rusts when it is exposed to ______________ and _____________.

8. Plastics do not react with ______________ and __________________.

9. Plastics are generally ___________________ than metals.

10. ________________ is a special plastic on which oil and water do not stick.

11. Fire-proof plastics have a coating of ________________ plastic on them to make them flame resistant.

12. We should always remember the 4R principle:________________, _____________ , _______________ and ____________________

Q2. Answer the following:

1. Define: i) a polymer ii) polyester iii) petrochemicals

2. Name a few synthetic fibres.

3. List the unique characteristics of synthetic fibres which make them popular dress materials.

4. Explain why plastic finds such a variety of uses.

5. Differentiate between thermoplastics and thermosetting plastics.

6. List the three characteristic properties of plastics.

7. What are the advantages of using a plastic container?

8. Why do electrical wires have plastic covering?

9. Why recycled plastic should not be used for storage of food?

10. Differentiate between a biodegradable and a non-biodegradable material.

11. Disposal of plastic is a major problem. Why?

12. List various ways by which we can reduce the use of plastic materials.

13. Anu and Manu go for shopping in the market and have chips, there is no dustbin around. What should they do with the empty packet of chips?