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

16. State the conditions essential for combustion to take place.

OR
Draw the cell for electrolytic reduction of alumina. Why is cryolite added to bauxite ? Name cathode and anode used in electrolytic cell. Why must the anodes be replaced from time to time ? Name the alloy used for making bodies of aircrafts. 3
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17. (i) Define Resistance and (ii) Resistivity. When a wire is made into four equal parts, find the resistance and resistivity of each portion. Give reason for your answer. 3
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18. (i) Stale the basic laws of electrolysis ?
(ii) How is it used for real life applications ? (iii) Explain with an example how chemical energy is used to produce electrical energy ?

OR
Explain the working of on electric motor with a neat labelled diagram.
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19. (a) Write IUPAC name of following compounds :
(i) CH₃CH₂CH₂OH (ii) CH₃COOC₂H₅
(iii) CH₃CHO (iv) CH₃COCH₂CH₂CH₃
(b) How is propanone prepared commercially ? Give the reactions involved in it. Give two uses of propanone. 5
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20. How is cement manufactured ? Give raw materials and composition of portland cement. Why is gypsum added to cement ? Give two of its uses.

OR
How is glass manufactured ? Give raw materials and composition of soda glass. What special compounds are added to get coloured glasses 7 Give two examples. 5
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Section - B

21. Define photosynthesis. 1
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22. What are the two types of blood vessels ? Which vessel works as an interconnector ? 1
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23. Where is glucagon secreted ? What is its function ? 1
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24. Give the full form of (a) OCs (b) AIDS © NGO (d) HIV.

OR
What are the two types of reproduction ? Give one point of difference between them. 2
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25. Name the nitrogenous bases found in DNA. 2
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26. What is meant by occupational diseases ? 3
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27. Explain briefly the respiration in plants. 3
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28. What are antigens and antibodies ? Why are they considered antagonistic to one another ? 3
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29. Describe the central nervous system in human beings. 3
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30. What is water pollution ? What are its causes and effects ? 5
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