Page 243 - ICSE Chemistry 8

15. What is sublima on?
16. What is mass number?
17. What is rela ve atomic mass?
18. Write the proper es of isotopes.
19. Write the electronic confi gura on of carbon, aluminium, phosphorus and potassium.
20. Diff eren ate between posi ve valency and nega ve valency.
21. Discuss valency of elements.
22. How is a ca on diff erent from an anion?
23. Write the symbols of the ions formed by the following elements: copper, sodium, chlorine and oxygen.
24. What is a balanced equa on?
25. What is the diff erence between a posi ve catalyst and a nega ve catalyst?
26. Diff eren ate between reactants and products.
27. What is the func on of the enzymes pepsin and maltase?
28. What is electric decomposi on?
29. What is displacement reac on?
30. How is calcina on diff erent from roas ng?
31. How is hydrogen prepared from steam?
32. Discuss the prepara on of hydrogen by the ac on of alkalis on metals.
33. What happens when hydrogen reacts with oxygen?
34. What happens when hydrogen reacts with carbon?
35. Write two chemical reac on where hydrogen acts as a reducing agent.
36. Write the uses of dis lled water.
37. Why does the boiling point of water increase with increase in pressure?
38. What is anomalous expansion of water?
39. Discuss the factors aff ec ng the forma on of a solu on.
40. What happens when metals react with steam?
41. Discuss the structure of diamond.
42. How is graphite prepared?
43. Write the uses of sugar charcoal.
44. Write the uses of lampblack.
45. Write the tests performed to check the presence of carbon dioxide.
D. Answer in detail.
1. Write a note on kine c molecular theory.
2. Write the proper es of liquids and gases.
3. With the help of an ac vity, show that total mass remains same during a physical change.
4. With the help of an ac vity, show that total mass remains same during a chemical change.
5. With the help of an ac vity, show that total mass of reactants is equal to the total mass of products
in a chemical reac on between barium chloride and sodium sulphate.
6. Why do we consider the following changes as physical changes?
(a) Drying of wet clothes (b) Mel ng of ice
7. With the help of an ac vity, show that cu ng of paper is a physical change.
8. What is sublima on. Explain sublima on of ammonium chloride.
9. What is a chemical change? Write the characteris cs of a chemical change.

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