Page 244 - ICSE Chemistry 8

10. Why do we consider the following changes as chemical changes?
(a) Rus ng of iron (d) Curdling of milk
11. Discuss the forma on of mixtures.
12. With the help of an ac vity, show how components of a mixture can be separated by winnowing.
13. Discuss the techniques of solvent extrac on and frac onal crystallisa on.
14. With the help of an ac vity, show how components of a mixture of CaCO and NaCl can be separated.
3
15. Write a note on combining methods for separa ng mixtures.
16. Write a note on discovery of proton. Write the characteris cs of protons.
17. Discuss Rutherford’s model of an atom.
18. Discuss the modern concept of an atom.
19. Discuss the discovery of neutron. Write the characteris cs of neutrons.
20. What is a chemical bond. Discuss the forma on of electrovalent compounds and covalent
compounds.
21. Balance the following chemical equa ons.
(a) Fe + O Fe O (b) CH + O CO + H O
2
4
2
2
2
3
2
22. Balance the chemical equa on that represents the dissocia on of water.
23. Balance the following chemical equa ons by applying the law of conserva on of mass.
(a) CaCO CaO + CO (b) Mg + O MgO
2
2
3
24. Discuss the informa on gathered from a chemical equa on with the help of an example.
25. Discuss the limita ons of a chemical reac on.
26. Write a note on decomposi on reac ons.
27. Diff eren ate between displacement reac on and double displacement reac on.
28. Write a note on redox reac on. Diff eren ate between oxidising and reducing agents.
29. Discuss how oxides are formed from decomposi on reac ons.
30. Discuss the classifi ca on of oxides.
31. Discuss the prepara on of hydrogen by electrolysis of water.
32. Discuss the Bosch’s process used to produce hydrogen on a large scale.
33. Write the physical proper es of hydrogen. With the help of an ac vity, show that hydrogen gas is
combus ble.
34. Write the chemical proper es of hydrogen. With the help of an ac vity, show that hydrogen gas is a
reducing agent.
35. Write the uses of hydrogen.
36. Write the chemical proper es of water.
37. How will you test the quality of tap water and dis lled water?
38. With the help of an ac vity, observe the forma on of scum in hard water and so water.
39. Discuss the causes of hardness of water and the disadvantages of hard water.
40. Discuss how hardness of water can be removed.
41. Discuss the proper es of buckminsterfullerene.
42. Discuss the forma on of coal and types of coal.
43. Write the physical and chemical proper es of carbon dioxide.
44. What is greenhouse eff ect? Write the eff ects of global warming.
45. Discuss the poisonous nature of carbon dioxide. Write the precau ons to be taken to avoid carbon
monoxide poisoning. Also discuss how carbon monoxide is added to the atmosphere.

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