Carbon: An Important Element
Q1. Why is carbon considered an important element?
A. Because it is the basis of life and forms a large number of compounds due to its catenation property.
Q2. What is the atomic number of carbon?
A. 6.
Q3. What is the valency of carbon?
A. 4 (tetravalent).
Q4. What is catenation?
A. The ability of carbon atoms to form long chains or rings by bonding with other carbon atoms.
Q5. Name the three major allotropes of carbon.
A. Diamond, graphite, and fullerene.
Q6. Why is diamond hard?
A. Because each carbon atom is covalently bonded to four other carbon atoms in a rigid 3D structure.
Q7. Why is graphite a good conductor of electricity?
A. Due to the presence of free electrons between its layers.
Q8. What is fullerene?
A. A spherical molecule made up of carbon atoms, e.g., C60 (buckyball).
Q9. What is an organic compound?
A. A compound containing carbon, usually bonded with hydrogen, oxygen, or other elements.
Q10. Give two examples of hydrocarbons.
A. Methane (CH₄) and Ethane (C₂H₆).
Q11. What is the functional group in alcohols?
A. –OH (hydroxyl group).
Q12. What is the functional group in carboxylic acids?
A. –COOH (carboxyl group).
Q13. Name the simplest ketone.
A. Propanone (acetone).
Q14. Name the simplest aldehyde.
A. Methanal (formaldehyde).
Q15. What is isomerism?
A. The phenomenon where compounds have the same molecular formula but different structures.
Q16. Give an example of a saturated hydrocarbon.
A. Methane (CHâ‚„).
Q17. Give an example of an unsaturated hydrocarbon.
A. Ethene (Câ‚‚Hâ‚„).
Q18. What is hydrogenation?
A. The process of adding hydrogen to unsaturated hydrocarbons in the presence of a catalyst.
Q19. What is saponification?
A. The process of making soap by reacting fat/oil with a base.
Q20. What is esterification?
A. The reaction between an alcohol and a carboxylic acid to form an ester and water.
Q21. Give one use of ethanol.
A. Used as a fuel and in alcoholic beverages.
Q22. Give one harmful effect of methanol.
A. It is poisonous and can cause blindness or death.
Q23. Why is carbon dioxide considered a greenhouse gas?
A. Because it traps heat in the Earth's atmosphere, contributing to global warming.
Q24. Give one use of graphite.
A. Used as a lubricant and in making electrodes.
Q25. Name one carbon compound used in perfumes.
A. Esters are used in perfumes due to their pleasant smell.
Q26. What is the molecular formula of ethanoic acid?
A. CH₃COOH.
Q27. Name one use of diamond other than jewellery.
A. Used in cutting tools due to its hardness.
Q28. What is the chemical formula of methane?
A. CHâ‚„.
Q29. Why is carbon able to form so many compounds?
A. Due to catenation and tetravalency.
Q30. Name one carbon compound used as an anaesthetic.
A. Chloroform (CHCl₃).