» CBSE Science Practice Paper : Set IV : CBSE Sample Question Papers

16. Write chemical equations to show what happens when :
(i) Sulphur powder is heated with cone H₂SO₄. (if) Cinnabar is roasted in a furnace (iii) Sulphur dioxide is dissolved in water. 3
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17. The heat produced by burning of cowdung cake of mass 210 g raised the temperature of 50 g of water by 2^°C, Assuming that all the heat was utilised for heating water whose specific heat capacity is 4.2 J/g^°C, Calculate the calorific value of Aid.

OR
Heat produced on buring 5.0 g of fuel raises the temperature of 1.0 Kg of water from 20^° to 60^° C. If the specific heat of water is 4.2 J/g ^°C, calculate calorific value of fuel. 3
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18. Explain the principle of working of a (i) Electric Motor and (it) A.C. Generator. 5 Write the basic rules used to explain their working.
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19. Explain the following terms giving an example :
(i) Addition reaction (ii) Tollen’s reagent test
(iii) Saponification (V) Decarboxylation
(v) Polymerisation.
OR
Explain fractional distillation of petroleum with the help of neat and labelled diagram. Name four fractions and give the uses of each fraction. 5
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20. State Ohm’s law. When two resistors R1 and R2 connected in parallel to a source of energy, find the equivalent resistance. In the circuit given below if R₁, R₂ and R₃ have 15 Ωt 30 Ω and 45 Ω respectively and the battery has 15 volt. Calculate (i) the equivalent resistance.
(ii) current drawn from battery,
(iii) the current through each resistor, (1+2+1 + 1)
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Section - B

21. What do you mean by evolution ?
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22. Which part of roots is involved in exchange of respiratory gases ?
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23. What do you understand by biological magnification ?
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24. What is the excretory waste in Amoeba and Earthworm ?

OR
What is the role of skin in excretion ?
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25. Differentiate between axon and dendron.
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26. What are the disadvantages of vegetative propagation ?
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27. Why did Mendel select garden pea for his experiments ?
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28. Differentiate between biodegradable and non-biodegradable pollutants.
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29. What arc the functions of plant hormones ?
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30. Describe the internal structure of the human heart. Where is pacemaker located and what is its function?

OR
Explain the various steps of coagulation of blood. 5
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