MSBSHSE Class 8 Science Chapter 17: Man Made Materials Important Textbook Questions and Solutions

We use various types of materials in our daily life. Those materials are made up of various materials like wood, glass, plastic, thread, soil, metals, rubber, etc. Out of those, wood, rock, minerals, water are natural. Humans performed research on various natural materials in laboratories. With the help of it, various materials are manufactured in factories.Such materials are called man made materials. eg. Glass, plastic, artificial threads,thermocol, etc.

MSBSHSE Class 8 Science Chapter 17 textbook solutions is considered as one of the best reference tools, which students can rely on blindly. These solutions are crafted by subject matter experts having extensive knowledge in the respective domain. For students MSBSHSE Class 8 solutions Chapter 17 are simple and easy to understand, which helps students in comprehending topics in no time.

MSBSHSE Class 8 Science Chapter 17 Objective Questions: Textbook Important Questions and Solutions

MSBSHSE Class 8 Science Chapter 17 Textbook Exercise Questions

Q1. Try to find it.

a. Plastic shows …… property, hence it can be moulded to any shape.

b. Motor cars are coated with …….

c. Thermocol melts at …… ºC.

d. …… glass dissolves in water.

Answer a: Plastic shows malleable property, hence it can be moulded to any shape.

Answer b: Motor cars are coated with Teflon.

Answer c: Thermocol melts at 240 ºC.

Answer d: Water glass dissolves in water.

Q2. Who is my partner?

‘A’ column

‘B’ column

Lead glass

Plates

Bakelite

Mattresses

Thermocol

Electric bulb

Optic glass

Electric switch

Polypropylene

Lens

Answer:

‘A’ column

‘B’ column

Lead glass

Electric bulb

Bakelite

Plates

Thermocol

Electric switch

Optic glass

Lens

Polypropylene

Mattresses

Q3. Answer the following.

a. Thermocol is produced from which material?

b. Write uses of PVC.

c. Write the natural or manmade raw material of the following items.

Mattress, glass vessel, bangle, chair, gunny bag, broom, knife, pen.

d. Which are the main ingredients of glass?

e. How is plastic produced?

Answer a: Thermocol is a form of a complex material called polystyrene. It transforms into a liquid state on heating at more than 100 ºC temperature and returns to solid state on cooling. Due to this, we can give any desired shape to it. Being a good shock-absorber, it is used in packing of delicate items.

Answer b: Polyvinyl chloride (PVC) is a plastic polymer made of monomer vinyl chloride. PVC are used for manufacturing toys, combs, plates, bowls etc.

Answer c:

Items

Natural raw material

Man made raw material

Mattress

Plastic

Beaker

Silica Glass

Bangles

Glass

Chair

PVC

Gunny Bags

Jute

Broom

Broomcorn

Knife

Steel, Metal

Plastic

Pen

Metal

Plastic

Answer d: Glass is the non-crystalline, hard but brittle solid material formed from mixture of silica and silicate. Silica i.e. SiO2 to which we refer to as sand. Depending upon the proportion of silica and other components in the glass; there are different types of glass as soda-lime glass,

boro-silicate glass, silica glass, alkali silicate glass, etc.

Answer e: A man made material showing the property of plasticity and made up of organic polymers is plastic. Structure of all the plastics is not the same. Some are linear while some are circular.

Q4. Distinguish between.

a. Manmade material and natural material

b.Thermoplastic and thermosetting plastic.

Answer a:

Differences between Natural and Manmade material

Natural Material

Manmade Material

Comes from nature

Man made material

Natural colour

Color as per requirement is added in colour bath

During spinning process spinneret is not necessary

During spinning process spinneret is necessary for the production of filament

Chances of containing dust or impurities

No chance of any dust or impurities

Less durable than synthetic

More durable than natural

Answer b:

Differences Between Thermoplastic and Thermosetting Plastic

Thermoplastic

Thermosetting Plastic

Thermoplastic can be synthesized by the process called addition polymerization.

Thermosetting plastics are synthesized by condensation polymerization.

Thermoplastic is processed by injection moulding, extrusion process, blow moulding, thermoforming process and rotational moulding.

Thermosetting Plastic is processed by compression moulding, reaction injection moulding.

Thermoplastics have secondary bonds between molecular chains.

Thermosetting plastics have primary bonds between molecular chains and held together by strong cross-links.

Thermoplastics have low melting points and low tensile strength.

Thermosetting plastics have high melting points and tensile strength.

Thermoplastic is lower in molecular weight, compared to thermosetting plastic.

Thermosetting Plastic is high in molecular weight.

5. Answer the following in your own words.

a. Explain the effect and remedial plans of following materials on environment and human health.

1. Plastic

2. Glass.

3. Thermocol.

b. Which measures will you arrange to minimize the environmental problems arising due to non-degradable plastic?

Answer a: The effects of the following materials on environment and human health are:

1) Plastic – It is non-biodegradable and a man made material which causes a lot of land pollution. Due to its non-biodegradable characteristics it remains in the soil and water for a very long time, thus causing pollution. The smoke released after burning of plastic is also harmful for human health.

2) Glass – While glass production, mixture needs to be heated up to 1500 ºC. During this, greenhouse gases like sulphur dioxide, nitrogen dioxide, carbon dioxide are released through burning of fuel. As the glass is non-degradable, if pieces of the waste glass material flow into water body, it may affect that ecosystem. Similarly, drainage may be blocked due to these pieces.

3) Thermocol – Being carcinogenic ingredients in styrene, the person in contact with thermocol for long duration may have the possibility of blood cancer like leukemia and lymphoma. It takes a long duration for natural degradation of thermocol; hence many people opt for destroying it by burning. However, it is still more hazardous method as it releases poisonous gases in atmosphere. In mass gatherings, plates and cups used to offer the food, water, tea are made up of thermocol. It affects their health. If the food kept in thermocol is reheated, styrene may dissolve in that food. Due to this, there is possibility of health problems.

Answer b:

Q6. Write short notes.

a. Glass production.

b. Optic glass

c. Uses of plastic.

Answer a: For glass production, mixture of sand, soda, lime, and small quantity of magnesium oxide is heated in furnace. Sand i.e. silicon dioxide melts at 1700 0C. So as to melt the mixture at low temperature, pieces of discarded glass are added to it. Due to this, mixture melts at 850 ºC. Once all the ingredients of mixture are liquified, it is heated up to 1500 ºC and immediately cooled. Due to sudden cooling, mixture becomes homogeneous, amorphous and transparent instead of crystalline. This is called Soda-lime glass.

Answer b: Optical glass is produced from the mixture of sand, soda, limestone, barium oxide and boron. This type of pure glass is useful in production of spectacles, lenses, microscopic lenses, etc.

Answer c: Following are the uses of plastics

  • Plastic is used in healthcare sector e.g. syringes.
  • Vessels used to cook food in microwave oven are made up of plastic.
  • Vehicles are coated with Teflon to protect from scratches. Teflon is a type of plastic.
  • There are more than 2000 different types of plastics.
  • Some types of plastic are used in assembling some parts of aeroplane.
  • Polyacrylic is a type of plastic used for manufacturing lenses & artificial teeth.

Q7. Write the properties of glass?

Answer: The properties of glass are as follows

  • On heating, glass becomes soft and can be moulded into any shape.
  • Density of glass depends upon its ingredients.
  • Glass is slow conductor of heat. On quick heating of cool glass or on quick cooling of hot
  • glass, it cracks / breaks.
  • Being bad conductor of electricity, glass is used as insulator in electric appliances.
  • Being transparent, most light passes through the glass. However, if there are oxides of either chromium, vanadium or iron in the glass, large amount of light is absorbed in glass.

Q8. Explain properties of plastics.

Answer: The properties of glass are:

  • Plastic does not corrode.
  • It does not decompose.
  • It is not easily affected by humidity, heat, rain, etc.
  • Items of any colour can be made from it.
  • It can be molded into any shape due to the property of plasticity.
  • It is a bad conductor of heat and electricity.
  • Being light in weight, it is easy to carry.

Q9. Define degradable and non-degradable material?

Answer: Some materials are naturally degraded, they are called degradable materials while some materials are not naturally degraded they are called non-degradable material.

Q10. How many types can plastics be classified into?

Answer: Depending upon the effect of heat, plastic can be classified into two types. The plastic that can be molded as per our wish is called thermoplastic. Eg. Polythene, PVC are used for manufacturing the toys, combs, plates, bowls etc. Another plastic is such that once a specific shape is given with the help of mold, its shape cannot be changed on heating. It is called thermosetting plastic. eg. Electric switches, coverings over the handles of cookers, etc.

Q11. Explain the uses of thermoplastic and thermosetting plastic?

Answer: The uses of thermoplastic and thermosetting plastic:

Thermoplastic

Polyvinyl chloride (PVC)

Bottles, raincoat, pipes, handbags, shoes, electric cable insulation, furniture, ropes, toys, etc.

Polystyrene (PS)

Thermo-insulating parts of electric appliances like refrigerators, gears of machines, toys, protective coverings like covers of CD and DVD, etc.

Polyethylene (PE)

Milk bags, packing bags, flexible garden pipes, etc.

Polypropylene (PP)

Parts of loudspeakers & vehicles, ropes, mattresses, laboratory appliances, etc.

Thermosetting plastic

Bakelite

Cabinets of radio, T.V., telephones, electric switches, toys, coverings over handles of cookers, etc.

Melamine

Domestically useful items like cup – saucers, plates, trey, some spare parts of airplane engines, electric and sound insulating coverings, etc.

Polyurethane

Surfing boards, small boats, furniture, seats in vehicles, etc.

Polyester

Fiberglass, toners of laser printers, textile industry, etc.

Q12. Explain the types of glass and uses.

Answer: The types and uses of glass are as follows:

Silica glass : This is produced by using the silica. Items made up of silica glass show minimum expansion on heating. It is not affected by acid and alkali. Due to this, silica glass is used to produce laboratory glass-wares.

Borosilicate glass : Borosilicate glass is produced by melting the mixture of sand, soda, boric acid and aluminium oxide. This glass does not show any effect on medicines. Hence, the bottles made up of borosilicate glass are used in pharmaceutical industry to store the medicines.

Alkali silicate glass : Alkali silicate glass is produced by heating the mixture of sand and soda. As this glass is soluble in water, it is called a ‘water glass’.

Lead glass is produced by melting the mixture of sand, soda, limestone and lead

oxide. Being very clear / transparent, it is used in manufacturing light bulbs, tubes, etc.

Optical glass : Optical glass is produced from the mixture of sand, soda, limestone, barium oxide and boron. This type of pure glass is useful in production of spectacles, lenses, microscopic lenses, etc.

Coloured glass : Soda lime glass is colorless. So as to impart a desired colour, oxide of specific metal is mixed during manufacturing process. eg. Ferrous oxide is mixed to get bluish green glass and copper oxide to get red glass.

Processed glass : So as to improve the quality and utility, some processing is performed on glass and various types like reinforced glass, plain glass, fiberglass, fen glass, translucent glass, etc. are produced.

Q13. Explain the harmful effects of plastic for the environment?

Answer: The harmful effects of plastic for the environment are as follows:

  • Littering of plastics in open spaces creates unhygienic conditions, as it acts as a breeding ground for insects and mosquitoes that cause diseases like malaria and dengue.
  • Plastics do not undergo degradation, thus, stay in the soil for many years, which affects the soil fertility and degrades the soil quality.
  • When plastic artifacts enter the drainage and sewerage system, they block the pipes and the drains causing waterlogging.
  • The improperly disposed food bags, when eaten by animals, cause stomach and intestine related disease which even lead to suffocation and death.
  • Plastic items find their way to the river and other water bodies, which are then swallowed by fish, seabirds, and other marine species, thus leading to suffocation and death.
  • The waste from the plastic manufacturing industry is thrown directly into the water bodies, thus affecting the chemical property of water, causing hazards on a very large-scale.

Q14. How can we manage plastic waste management?

Answer: There are primarily three ways of managing plastics:

  • Reduce
  • Reuse
  • Recycle

Reduce

This refers to the reduction or decreased consumptions of plastic artifacts.

  • We can reduce the use of plastic bags and carry jute bags and paper bags to carry items from the market.
  • We can reduce the use of plastic containers for storing food and other items and use more durable materials like metal.
  • We can avoid using takeaway food containers.

Reuse

  • We can use discarded bottles and jars to store food items and water.
  • We can reuse the plastic bags whenever possible, keeping safety and hygiene in mind.
  • We can use broken artifacts and create something new with our own creativity, for e.g. discarded water bottles can be used as containers, as shown in the figure below.

Recycle

  • We can give the old plastic chairs and jars for a recycle and support the cause by using recycled items.
  • We can try using recyclable plastic bags, whenever possible.

Q15. Explain the advantages of plastic.

Answer: The following properties of plastic make it the material of choice for making many articles:

Plastics are non-reactive: Most of the metals get corroded by air and water. But plastics do not react with air or water. So, they cannot be corroded easily. Therefore, it is used for making many utensils and storing various chemicals.

Plastics are light, strong and durable: The articles made up of plastics are very light. Plastic being light, strong and durable can be molded into many shapes and sizes as required by the user. They are cheaper than metals and hence, widely used in making various household products.

Plastic is a poor conductor: They are poor conductors of heat and electricity and therefore plastics are used for coating electric wires and switches. The handles of frying pans are also made up of plastic due to this property.

Q16. What is glass?

Answer: Glass is the non-crystalline, hard but brittle solid material formed from mixture of silica and silicate. Silica i.e. SiO2 to which we refer to as sand. Depending upon the proportion of silica and other components in the glass; there are different types of glass such as soda-lime glass, boro-silicate glass, silica glass, alkali silicate glass, etc.

Q17. Write the effect on persons working in thermocol factories?

Answer: Persons staying in contact with thermocol for long term may develop the problems of eyes, respiratory system, skin, digestive system, etc. Pregnant women may face miscarriage. Liquid styrene may cause skin-burns.

Q18. Which material is wrapped around the items of glass or similar material during transport to prevent from breaking up?

Answer: Bubble wrap is used around the items of glass or similar material during transport to prevent from breaking up. Glass or other similar material are fragile in nature. Bubble wrap has

got air bubbles, which prevent the glass ware from shock that might lead to breakage.

Q19. Which type of glass is used in vehicles to avoid injuries in accidents?

Answer: Glass used in making car is called safety glass. The glass used in the windshield is laminated glass. These are all special types of glasses which are used for making cars so that they don’t break easily, and when they break they don’t cause much injury.

Q20. What is a plastic?

Answer: A man made material showing the property of plasticity and made up of organic polymers is plastic. Structure of all the plastics is not the same. Some are linear while some are circular.

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