Substances in Common Use
Q1. What is polymerisation?
A. The process in which small molecules (monomers) join to form large molecules (polymers).
Q2. Give two examples of natural polymers.
A. Cotton (cellulose) and silk.
Q3. Give two examples of synthetic polymers.
A. Nylon and polythene.
Q4. What is thermoplastic?
A. A type of plastic that softens on heating and hardens on cooling, e.g., polythene.
Q5. What is thermosetting plastic?
A. A plastic that once set cannot be remoulded, e.g., bakelite.
Q6. Why is Teflon used in non-stick cookware?
A. Because it has a very low coefficient of friction and is heat resistant.
Q7. What is vulcanisation of rubber?
A. The process of heating natural rubber with sulphur to improve its strength and elasticity.
Q8. Give one use of bakelite.
A. Used in making electrical switches and handles of utensils.
Q9. What is rayon?
A. Rayon is a regenerated fibre made from cellulose.
Q10. Why is nylon stronger than silk?
A. Because nylon fibres are made by strong chemical bonds in a regular structure.
Q11. Name two biodegradable substances.
A. Paper and cotton.
Q12. Name two non-biodegradable substances.
A. Plastic and polythene.
Q13. Why should plastic be recycled?
A. To reduce environmental pollution and conserve resources.
Q14. What is polyester?
A. A synthetic fibre made from repeating ester units, e.g., PET.
Q15. Name one polyester fabric.
A. Terylene.
Q16. What is melamine used for?
A. Used in making unbreakable kitchenware.
Q17. Why is PVC used in making pipes?
A. Because it is strong, durable, and resistant to corrosion.
Q18. Name one use of neoprene.
A. Used in making wetsuits and hoses.
Q19. What is cellophane made from?
A. Regenerated cellulose.
Q20. Give one property of natural rubber.
A. It is elastic and can be stretched.
Q21. What is the main raw material for making glass?
A. Silica (sand).
Q22. Name two types of glass.
A. Soda-lime glass and borosilicate glass.
Q23. What is the use of borosilicate glass?
A. Used in laboratory glassware and kitchenware because it resists heat.
Q24. Name one harmful effect of plastic.
A. It causes environmental pollution as it is non-biodegradable.
Q25. Give one advantage of synthetic fibres over natural fibres.
A. They are stronger and more durable.
Q26. Give one disadvantage of synthetic fibres.
A. They melt on heating and can cause burns.
Q27. Name one plastic used in making bulletproof vests.
A. Kevlar.
Q28. What is polythene used for?
A. Used in making carry bags and packaging material.
Q29. Give one environmental problem caused by polythene.
A. It blocks drains and harms aquatic life.
Q30. Name one synthetic fibre used in parachutes.
A. Nylon.