General Science Important Questions Chapter 17 Man made Materials Class 8 Maharashtra Board

Imp Questions For All Chapters – General Science Class 8

Short Questions

1. What are man-made materials?

• Materials that are created by humans using natural substances.

2. Give two examples of man-made materials.

• Plastic and glass.

3. What are natural materials?

• Materials that exist naturally in the environment.

4. Give two examples of natural materials.

• Wood and cotton.

5. What is plastic made from?

• Plastic is made from petroleum and natural gas.

6. What is polymerization?

• A process in which small molecules (monomers) join together to form large chains (polymers).

7. What are the two types of plastics?

• Thermoplastics and thermosetting plastics.

8. What is the difference between thermoplastic and thermosetting plastic?

• Thermoplastic can be reshaped, while thermosetting plastic cannot be reshaped after molding.

9. Give two examples of thermoplastics.

• PVC (Polyvinyl chloride) and Polythene.

10. Give two examples of thermosetting plastics.

• Bakelite and Melamine.

11. What is glass made from?

• Glass is made from sand (silica), soda (sodium carbonate), and lime (calcium carbonate).

12. What are the uses of glass?

• Used in windows, bottles, lenses, mirrors, and utensils.

13. What is Thermocol made from?

• Thermocol is made from polystyrene.

14. Why is plastic harmful to the environment?

• Plastic is non-biodegradable, causing pollution and harming animals.

15. What is PVC used for?

• Used in pipes, raincoats, shoes, toys, and electrical insulation.

16. What is optic glass?

• A pure form of glass used in lenses, microscopes, and cameras.

17. What is lead glass used for?

• Used in electric bulbs and radiation shielding.

18. How can we reduce plastic pollution?

• By recycling, reusing, and using biodegradable materials.

19. Why are Teflon coatings used in cookware?

• Teflon is non-stick and heat-resistant, making it ideal for cookware.

20. What are the main ingredients of glass?

• Silica (sand), soda, and lime.

Long Questions

1. What are the differences between natural and man-made materials?

• Natural materials like wood and cotton are found in nature, while man-made materials like plastic and glass are created by humans. Man-made materials are often more durable and flexible than natural ones.

2. What are the harmful effects of plastic on the environment?

• Plastic is non-biodegradable and causes land and water pollution. It harms animals when they mistakenly eat plastic waste, and burning plastic releases toxic gases.

3. What are thermoplastics and thermosetting plastics?

• Thermoplastics like PVC and polythene can be reshaped when heated. Thermosetting plastics like Bakelite and Melamine become hard after molding and cannot be reshaped.

4. How is glass made?

• Glass is made by heating sand (silica), soda, and lime at high temperatures (850°C – 1500°C). The molten mixture is then cooled quickly to form a transparent solid.

5. Why is glass useful in making lenses and mirrors?

• Glass is transparent and can be polished, making it ideal for lenses and mirrors. It is also chemically stable, meaning it does not react with air or water.

6. What are the effects of plastic and Thermocol on human health?

• Plastic releases harmful chemicals that can cause health problems. Burning Thermocol produces toxic gases, leading to breathing issues and pollution.

7. How can we reduce the use of plastic in daily life?

• We can use cloth or jute bags instead of plastic bags and avoid plastic cutlery. Recycling and switching to biodegradable materials can help reduce plastic waste.

8. Why is Teflon used for coating utensils?

• Teflon is non-stick, heat-resistant, and does not react with food, making cooking easier. It helps in reducing oil usage and prevents food from sticking to utensils.