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Grade 10 Chemistry Notes – Chapter 10 Hydroxy Compounds

Chemistry Notes – Grade 10

National Curriculum Pakistan - NCP

Chapter 10: Hydroxy Compounds

Aligned with National Curriculum Pakistan (Federal Board, NBF, PTB)

Hydroxy Compounds Questions and Answers


  1. What is fermentation?
    Fermentation is a process where yeast converts glucose into ethanol and carbon dioxide in the absence of oxygen.
  2. Write the equation for fermentation of glucose.
    C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
  3. How is absolute ethanol obtained?
    By using a dehydrating agent like concentrated H₂SO₄ to remove water from rectified spirit.
  4. Why is fermentation considered an environmentally friendly method for ethanol production?
    It uses renewable plant materials, low energy, and emits fewer greenhouse gases, making it sustainable and eco-friendly.
  5. What are the drawbacks of using hydration of ethene for ethanol production?
    It depends on crude oil, uses high energy, and has low ethene conversion efficiency (only about 4% per pass).
  6. Why does ethanol need to be purified after fermentation?
    Because fermentation produces only 10–15% ethanol mixed with water and impurities, needing distillation and dehydration for purification.
  7. How does the structure of alcohols make them suitable as fuels?
    Their hydrocarbon chains enable easy combustion, releasing energy, CO₂, and water—similar to fossil fuels.
  8. How does ethanol help reduce air pollution when used as a fuel?
    It burns cleaner than petrol, producing less carbon monoxide and fewer pollutants, improving air quality.
  9. What makes alcohols suitable for pharmaceutical applications?
    They dissolve both water-soluble and fat-soluble substances and act as disinfectants, making them ideal for use in medicines and sterilization.
  10. Why is methanol less suitable for direct use in engines than ethanol?
    Methanol is more toxic, has lower energy output, and is corrosive to engines, requiring careful handling.
  11. How do alcohols act as antiseptics and disinfectants?
    They denature microbial proteins and disrupt cell walls, killing bacteria, viruses, and fungi effectively.
  12. What are the environmental concerns with using fossil fuels instead of alcohols?
    Fossil fuels are non-renewable and release large amounts of CO₂, causing global warming. Alcohols are renewable and burn cleaner.
  13. Why is ethanol used in the cosmetic industry?
    Because of its antibacterial, antiviral, antimicrobial, and antifungal properties.
  14. Name any three cosmetic products that contain alcohol.
    Deodorants, perfumes, and skin lotions.
  15. How do alcohols help cosmetic products?
    They prevent ingredient separation and improve the product’s ability to adhere to the skin.
  16. How do alcohols contribute to hygiene?
    They kill germs and are widely used in disinfectants and cleaning agents.
  17. Name one situation where alcohol-based disinfectants are very important.
    During pandemics like COVID-19.
  18. Why are alcohol-based disinfectants easy to use?
    They dry quickly and can be applied to many surfaces.
  19. What enzymes do in fermentation?
    They convert glucose into ethanol and carbon dioxide.
  20. What is the ethanol concentration after fermentation?
    10–15%.
  21. At what conditions is ethanol produced from ethene?
    At 300°C and 6000 kPa using phosphoric acid as a catalyst.
  22. What is rectified spirit?
    Ethanol that is 96% pure, separated by distillation.
  23. What is gasohol?
    A fuel made by blending 10–20% ethanol with petrol.
  24. Why is ethanol better than gasoline in some ways?
    It has a higher octane number and emits fewer harmful gases.
  25. What is the source of glucose used in fermentation?
    Plants such as sugar cane (a renewable source).
  26. How is ethanol made from ethene?
    By adding steam to ethene at 300°C and 6000 kPa using phosphoric acid as a catalyst.
  27. Write the equation for the hydration of ethene.
    C₂H₄ + H₂O → C₂H₅OH
  28. What percentage of ethene is converted into ethanol in hydration?
    Only 4%.
  29. Which method uses renewable resources—fermentation or hydration?
    Fermentation.
  30. What is the raw material in the hydration of ethene?
    Ethene from crude oil (non-renewable source).
  31. What is the raw material in the fermentation of glucose?
    Glucose from plants like sugar cane (a renewable source).
  32. Which process is faster—hydration or fermentation?
    Hydration.
  33. Which process produces pure ethanol?
    Hydration of ethene.
  34. Which method requires more energy?
    Hydration of ethene due to high temperature and pressure.
  35. Why do alcohols burn in air?
    Due to the presence of a hydrocarbon chain.
  36. Write the combustion reaction of ethanol.
    C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O + heat
  37. Which alcohol is used as an alternative fuel for cars?
    Methanol.
  38. What is gasohol?
    A fuel mixture of ethanol and gasoline.
  39. What is one advantage of ethanol fuel?
    It reduces emissions of carbon monoxide and other pollutants.
  40. How much can corn-based ethanol reduce greenhouse gas emissions?
    By roughly 40–50%.
  41. What is the disadvantage of using alcohol as fuel?
    They can corrode engine materials due to being highly hygroscopic.
  42. Name two alcohols used as solvents in pharmacy.
    Ethanol and isopropanol.
  43. What is isopropyl alcohol used for?
    Disinfecting and sterilizing surfaces and equipment.
  44. What property makes alcohols useful against microbes?
    They have antibacterial and antifungal properties.
  45. How do alcohols help in making medicines?
    They dissolve active ingredients, making them easier to use.
  46. What are alcohol swabs used for?
    To disinfect skin before injections or surgery.

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