Kerala Syllabus Class 8 Basic Science - Chapter 15 Chemistry of Matter - Questions and Answers
Questions and Answers for Class 8th Chemistry (English Medium) മാറ്റങ്ങളുടെ രസതന്ത്രം | SSLC Text Books Solution Basic Science (English Medium) Chapter 15 Chemistry of Matter - Simplified Class Notes - PPT
എട്ടാം ക്ലാസ്സ് Basic Science ലെ Chemistry of Matter എന്ന പാഠം ആസ്പദമാക്കി തയ്യാറാക്കിയ ചോദ്യോത്തരങ്ങള്.
Class 9 Basic Science - Chemistry of Matter - Question Bank
∎Basic Science (English Medium Notes)
♦ Look at the pictures. These materials are familiar to you. List them as described. 
Answer:
| Items made from natural materials | Items made from synthetic materials |
|---|---|
| • Door – Made of wood | • Jar - Made of glass |
| • Coir - Coconut fibre | • Balloon, tyre - Rubber |
| • Bamboo chair - Bamboo | • Bucket - Plastic |
| • Mixer grinder | • Plastic rope - Plastic |
| • Vessels - Aluminium, steel | |
| • Plastic Chair - Plastic | |
| • Hammer - Iron |
♦ What is Material Chemistry
Answer: Material Chemistry is a branch of science that helps in transforming various substances into useful products for humans.
♦ Which of the following is a man-made material?
a. Iron knife
b. Aluminium vessels
c. Glass test tube
d. Gold jewelry
Answer: c. Glass test tube
♦ Objects made of glass are essential part of our daily life. You know that glass is a synthetic material.
Try writing down the items made of glass:
• Mirror
• Glass jar
• Prism
• Windoglass
• Lenses
• Beaker
• Vehicle glass
The silicon dioxide in the sand undergoes a chemical reaction with metal salts at high temperature, forming glass.
♦ Which of the following is not a polymer?
a. Bakelite
b. PVC
c. Rubber
d. Copper
Answer: d. Copper
♦ Which of the following is the glass used to make lenses?
a. Soda glass
b. Flint glass
c. Hard glass
d. Borosilicate glass
Answer: b. Flint glass
♦ A table showing some types of glass used today, their uses and their major components is given.
| Types of Glasses | Uses | Major Components |
|---|---|---|
| Soda lime glass/ Soft glass | To make mirrors, window glass, bottles, etc. | Silica, Sodium oxide, Calcium oxide |
| Borosilicate Glass | To make laboratory equipment, cookware, etc. | Silica, Boron oxide, Sodium oxide/Potassium oxide |
| Flint Glass / Optical Glass | Used in the manufacture of lenses, prisms, etc. | Silica, Lead oxide, Potassium Carbonate |
♦ Which is the component present in all types of glass?
Answer: Silica (SiO₂/sand) is the common component of all types of glasses.
♦ What are the common properties of glass?
Answer:
• Transparency
• Hardness
• High density
♦ We use different types of glasses for different purposes.
a) Write any two general properties of glasses.
Answer:
• Transparency
• Hardness
♦ Which glass is used to make laboratory equipment?
Answer:
• Borosilicate Glass
♦ What are the components of borosilicate glass?
Answer: Silica, Boron oxide, Sodium oxide/Potassium oxide
♦ What is the salt used to give the glass a blue colour?
Answer: cobalt oxide (CoO)
♦ Haven’t you seen glasses of different colours? How do they get their colour?
Answer:
Glasses get a variety of colours when different chemicals are added during the manufacturing process.
| Chemicals Added | Colour of the Glass Obtained |
|---|---|
| • Cadmium sulphide | • Yellow |
| • Gold chloride | • Ruby red |
| • Chromium oxide | • Green |
| • Cobalt oxide | • Blue |
♦ What is a polymer?
Answer: Polymers are large and heavy molecules formed by combining small molecules called monomers.
♦ What is Polymerisation?
Answer: Polymerisation is the process in which small molecules combine under high pressure and temperature to form large molecules.
♦ Polymer chemistry
Answer: The branch of chemistry that studies polymers is called polymer chemistry.
♦ What is a monomer?
The small molecules that are used in polymerisation are called monomers.
♦ Which is the first synthetic polymer?
Answer: Bakelite is the first synthetic polymer.
♦ Who is considered the Father of Polymer Chemistry?
Answer: Hermann Staudinger, who laid the foundation for modern polymer chemistry, is known as the Father of Polymer Chemistry.
♦ Plastic tables, chairs, etc. can be manufactured easier than wooden ones. Why?
Answer: Polymers possess properties such as being moulded into any form and shape, imparting beautiful colours, and resisting decomposition in nature over long periods of time.
♦ Analyse the statements given below and choose the correct answer
Statement (A): Plastics are widely used in the manufacture of electrical switches and appliance handles.
Reason (R): Plastics are good conductors of heat and electricity.
a) A and R are correct, and R is the correct explanation of A.
b) A and R are correct, but R is not the correct explanation of A.
c) Statement A is correct, but R is false.
d) Statement A is false, but R is correct.
Answer: c) Statement A is correct, but R is false.
♦ Analyse the statements given below and choose the correct answer
Statement (A): Thermoplastics can be reshaped when heated.
Reason (R): Thermoplastics become soft when heated and hard when cooled.
a) A and R are correct, and R is the correct explanation of A.
b) A and R are correct, but R is not the correct explanation of A.
c) Statement A is correct, but R is false.
d) Statement A is false, but R is correct.
Answer:
a) A and R are correct, and R is the correct explanation of A.
♦ Observe the table showing some polymers, their characteristics and uses.
| Polymers | Characteristics | Uses |
|---|---|---|
| Polyethylene (Polythene) | Inert nature | Food containers, packaging |
| Polytetrafluoroethylene (PTFE) | Heat resistance | Cookwares used at high temperatures (Non-stick) |
| Polyvinyl chloride (PVC) | Electrical resistance | Cables, Pipes |
| Polyethylene terephthalate (PET) | Prevents gas permeation | Used in bottle manufacturing |
♦ Polymers are of natural and synthetic types. Most polymers are synthetic.
| Natural polymers | Synthetic polymers |
|---|---|
| • Cellulose • Starch • Natural rubber | • Polythene • Nylon • Bakelite • PVC • Synthetic rubbers |
♦ How can polymers be classified based on their physical properties?
Answer: Polymers can be classified into plastics, rubber, and fibres.
♦ Plastics can be further classified based on their nature into -------------- and ---------------------
Answer: Thermoplastics and thermosetting plastics.
♦ What are the unique properties of plastic materials that natural materials do not have?
Answer:
• Can be reshaped
• Moulded into any shape
• Give any colours
• Produced any size
• Change the properties
♦ What is the difference between thermoplastics and thermosetting plastics?
Answer:
• Thermoplastics and thermoplastic products can be reheated, melted and reshaped into new products.
Eg: Polythene, PVC, Polypropene, etc.
• Thermosetting plastics or thermosets are plastics that cannot be reheated and melted to make new, reshaped products.
Eg: Bakelite, Melamine formaldehyde
♦ Plastic products are usually marked with symbols and codes that help identify the type of plastic.
| Code | Abbreviation |
|---|---|
| • 1 | • PET |
| • 2 | • HDPE |
| • 3 | • PVC |
| • 4 | • LDPE |
| • 5 | • PP |
| • 6 | • PS |
| • 7 | • OTHER |
♦ Analyse the statements given below and choose the correct answer
Statement (A): Plastics are not biodegradable.
Reason (R): Microorganisms cannot decompose plastics.
a) A and R are correct, and R is the correct explanation of A.
b) A and R are correct, but R is not the correct explanation of A.
c) Statement A is correct, but R is false.
d) Statement A is false, but R is correct.
Answer: a) A and R are correct, and R is the correct explanation of A.
♦ Analyse the statements given below and choose the correct answer
Statement (A): Burning plastics in open spaces can cause air pollution.
Reason (R): Burning plastics releases toxic gases.
a) A and R are correct, and R is the correct explanation of A.
b) A and R are correct, but R is not the correct explanation of A.
c) Statement A is correct, but R is false.
d) Statement A is false, but R is correct.
Answer: a) A and R are correct, and R is the correct explanation of A.
♦ Find the relation and fill suitably
Polythene: Thermoplastic
Bakelite: ...............................
Answer: Thermosetting plastic.
♦ Find the relation and fill suitably.
Lens: Flint glass
Window glass: ...............................
Answer: Soda glass
♦ Which of the following plastics is used in non-stick cookware?
a) Polyethylene
b. Polytetrafluoroethylene
c. Nylon
d. P. V. C
Answer: b. Polytetrafluoroethylene (PTFE).
♦ Match the following and choose the correct answer.
| P. Polythene | S. Elastic polymer | X. Fishing net |
| Q. Natural Rubber | T. Fibre | Y. Thermoplastic |
| R. Nylon | U. Plastic | Z. Natural fibre |
P-U-X, Q-S-Y, R-T-Z
P-S-X, Q-U-Y, R-T-Z
P-U-Y, Q-S-Z, R-T-X
P-T-Z, Q-U-X, R-S-Y
Answer: P-U-Y, Q-S-Z, R-T-X.
♦ Some statements related to plastics are given below. Analyse them and choose the
(i). All plastics are thermosets.
(ii) Plastic is a polymer.
(iii) All plastics have the same properties.
(iv) Plastic is a biodegradable polymer.
(v). Polyethylene is an inert plastic.
a) Statements (i), (ii), (iii), (iv) and (v) are false.
b) Statement (i) is true, but statements (ii), (iii), (iv) and (v) are false.
c) Statements (ii) and (v) are true, but statements (i), (iii) and (iv) are false.
d) Statement (ii) is true, but statements (i), (iii) and (iv) are false.
Answer: The correct answer is c) Statements (ii) and (v) are true, but statements (i), (iii) and (iv) are false.
♦ There are man-made polymers and natural polymers available.
a) Write two examples of man-made polymers.
Answer:
• Polythene
• Nylon
b) Write two examples of natural polymers.
Answer:
• Cellulose
• Starch
♦ Plastic Pollution
Plastic is something unavoidable due to its diverse benefits. However, due to uncontrolled use, plastics and plastic products accumulate in various places, causing water and soil pollution. As a result, the natural chemical composition of soil, air, and water is altered. It affects the growth of plants and organisms living in the soil.
♦ Explain the 4Rs that can be used to reduce pollution caused by plastic?
• Refuse – Avoid giving or accepting plastic products.
• Reduce – Minimise the use of plastic products.
• Reuse – Reuse plastic products.
• Recycle – Convert plastic products into new items through suitable physical and chemical processes.
♦ Rubbers
Natural rubber is an elastic natural polymer. Natural rubber is obtained from the latex collected from the rubber tree. When the demand increased, natural rubber alone was not sufficient to meet it. This led to the production of synthetic rubbers. Moreover, synthetic rubber shows less wear and tear compared to natural rubber. That is why synthetic rubbers are used in the manufacture of tyres.
♦ Write reasons why synthetic rubbers is used in the manufacture of tyres.
Answer: Synthetic rubber shows less wear and tear compared to natural rubber. That is why synthetic rubbers are used in the manufacture of tyres.
♦ Fibres
Fibres are polymers that are strong and long. Apart from clothing, they are used to make ropes, mats, nets, etc. Artificial fibres were developed to overcome the limited availability and quality issues of natural fibres. Today, the universal availability of clothing and the diversity in the textile field is due to synthetic fibres. Nylon is the first synthetic fibre made by humans. For a polymer to be considered a fibre, its length must be at least a hundred times of its diameter.
Fibres consist of natural fibres and synthetic ones. Each has its own advantages and limitations. To overcome these limitations, natural fibres are blended with synthetic fibres.
Natural fibres: Cotton, Silk, Jute, Coir
Synthetic fibres: Polyester, Nylon, Terylene (Dacron)
♦ Complete the table based on the characteristics of natural and synthetic fibres.
| Characteristics | Natural Fibres | Synthetic Fibres |
|---|---|---|
| Air circulation | More | Less |
| Water absorption ability | More | Less |
| Durability | Less | More |
| Weight | More | Less |
♦ What are the uses of fibres?
Answer:
• Can be used to prevent soil erosion and to make geotextiles for agricultural use.
• Nylon fibres are used to make fishing nets.
• Making ropes
• Making textiles
♦ Complete the table based on their characteristics.
| Characteristics | Polymer |
|---|---|
| • Suitable for making strong threads | • Fibres |
| • Polymer that can be moulded into various shapes | • Plastic |
| • Polymer with elastic nature | • Rubber |
♦ List the other materials around us that are made with the help of chemistry.
Answer:
• Dyes
• Perfumes
• Soaps
• Toothpastes
• Medicines
♦ Which was the first synthetic fibre made by man?
Nylon
♦ Thermosets are used to make handles of cooking utensils. Why?
Thermosets are used to make handles of cooking utensils because once they are moulded and set, they become hard and heat‑resistant. Unlike thermoplastics, they do not soften when heated, which makes them safe for handling hot cookware.
Let’s Assess
1. Which of the following is made of a synthetic material?
a. Iron nail
b. Aluminium vessel
c. Glass test tube
d. Gold ornament
Answer: c. Glass test tube
2. Which of the following is not a polymer?
a. Bakelite
b. PVC
c. Rubber
d. Copper
Answer: d. Copper
3. What is the difference between thermoplastics and thermosets?
Thermoplastics and thermoplastic products can be reheated, melted and reshaped into new products. However, thermosetting plastics or thermosets cannot be reheated and melted to make new reshaped products.
4. Write one reason why synthetic rubber is used in the manufacture of tyres.
Answer: less wear and tear
5. What is the advantage of blending natural fibres along with synthetic fibres?
When natural substances are mixed with artificial fibres, their character changes. The ability to absorb water increases. Ability to control temperature increases. Increase the possibility of bio-decomposition.
6. “Material chemistry provides us with both advantages and disadvantages” Do you agree with this statement? Why?
Yes, I agree. Material chemistry brings advantages like creating plastics, fibres, and advanced materials that improve daily life, but it also has disadvantages such as pollution and waste management issues. The key is to use these materials responsibly and develop eco‑friendly alternatives.
.webp)
.webp)
 Chapter 15 Chemistry of Matter - Questions and Answers){kind=link}
0 Comments