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”Read the instructions carefully before answering”
·
Try to answer in your own words as far as possible.
·
Include diagrams wherever required.
·
Diagrams should be drawn and
labeled with pencil only.
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1 marks X 9 = 9 marks (A)
1. Why should a magnesium ribbon be cleaned before
burning in air?
2. Why do ionic compounds have high melting points?
3. Why does an aqueous solution of an acid conduct
electricity?
4. What processes would you consider essential for
maintaining life?
5. Which part of the brain maintains posture and
equilibrium of the body?
6. What is meant by saying that the potential difference
between two points is 1 V?
7. What is a good source of energy?
8. What is a good fuel?
9. What is the role of the acid in our stomach?
2 marks X 9 =
18 marks (B)
10. Why does the colour of copper sulphate solution change
when an iron nail is dipped in it?
11. Why should curd and sour substances not be kept in
brass and copper vessels?
12. What are plant hormones? Give two examples?
13. Why is the use of iodised salt advisable?
14. How is the small intestine designed to absorb digested
food?
15. A current of 0.5 A is drawn by a filament of an
electric bulb for 10 minutes. Find the amount of electric charge that flows
through the circuit.
16. Draw magnetic field lines around a bar magnet.
17. If you could use any source of energy for heating your
food, which one would you use and why?
18. what are the disadvantages of fossil fuels?
3 marks x 6 = 18 marks (C)
19. 3. Identify the substances that are oxidised and the
substances that are reduced in the following reactions.
20. (i) 4Na(s) + O2(g) → 2Na2O(s)
(ii) CuO(s) + H2(g) → Cu(s) + H2O(l)
21. What are the different ways in which glucose is
oxidized to provide energy in various organisms?
22. What is a balanced chemical equation? Why should
chemical equations be balanced?
23. What will happen if a solution of sodium
hydrocarbonate is heated? Give the equation of the reaction involved.
24. Compare and contrast bio-mass and hydro electricity as
sources of energy.
5 marks X 3 = 15 marks (D)
25. Write the balanced chemical equations for the
following reactions.
(a) Calcium hydroxide + Carbon dioxide → Calcium
carbonate
+ Water
(b) Zinc + Silver nitrate → Zinc nitrate + Silver
(c) Aluminium + Copper chloride → Aluminium chloride +
Copper
(d) Barium chloride + Potassium sulphate → Barium sulphate
+
Potassium chloride
26. Describe double circulation in human beings. Why is it
necessary?
27. (1) The potential difference between the terminals of
an electric heater is 60 V when it draws a current of 4 A from the source. What
current will the heater draw if the potential difference is increased to 120 V?
(2) Resistance
of a metal wire of length 1 m is 26 Ω at 20°C. If the diameter of the wire is
0.3 mm, what will be the resistivity of the metal at that temperature? Using
Table 12.2, predict the material of the wire.
Total
marks = 9(A) + 18(B) + 18(C) + 15(D) = 60 marks
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