Section - A
1. How is the rate of reaction influenced by
(i) raising the temperature of reactants ?
(ii) adding to the reacting mixture a product of reaction without change in volume ? 1
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2. How are the molecules of aldehydes and ketones structurally different ? 1
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3. Name one non-metal and one metal which are in liquid state at room temperature. 1
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4. Name two other planets of the Solar System which are similar to the Earth in composition and structure.1
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5. How is the strength of the magnetic field at a point near a wire related to the strength of the electric current flowing in the wire ? 1
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6. How is chloride of lime chemically different from calcium chloride ? Why does chloride of lime gradually lose its chlorine when kept exposed to air ? 2
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7. What is formalin ? How does it react with Tollen’s reagent ? State any one of its uses.
OR
Complete the following reaction equations :
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8. What is a galaxy ? Name two common shapes of galaxies. Why is our galaxy called Milky War ? 2
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9. State one point of difference between a natural satellite and an artificial satellite. Name the type of orbit suitable for a geostationary satellite. 2
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10. Give one example of a nuclear fusion reaction. Describe one method for making such reactions possible. 2
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11. State Arrhenius’ concept of acids and bases. Giving reason, select a strong acid and a weak base from amongst the following substances :
H2CO3, HNO3, NaOH, NH4OH 3
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12. How is it that we can use detergents for washing clothes even when the water is hard, but not soaps ? What change has been made in the composition of detergents to make them biodegradable ?
OR
What is a polymer ? How have been polymers been classified ? Name one polymer for each of the following applications : (i) For insulating electric wires. (ii) For non-stick coatings on kitchen utensils. (iii) For blending with cotton to make shrink-resist cloth. 3
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13. Give reasons for the following :
(i) Silicon counts among metalloids.
(ii) Carbon is not used for making aluminium from aluminium oxide.
(iii) For making hydrogen by reaction with hydrochloric acid, granulated zinc is preferred to a block of zinc. 3
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14. Write chemical equations for reactions taking place when :
(i) Zinc carbonate is calcined.
(ii) Ammonia gas is passed over heated copper (II) oxide. (iii) SO2 gas and H2S gas are together bubbled through water. 3
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15. What are electrolytes ? Define Faraday’s constant for electrolytic reactions. Find chemical equivalents of Cu(II) (at. wt. 63.5) and Ag(I) (at. wt. 108). 3
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CBSE Science Examination Question Paper-2004
Filed under:
Class X
Social Science
Class Xth Previous Year Question Papers
16. The radius of curvature of a convex mirror used on a moving automobile is 2.0 m. A truck is coming behind it at a constant distance of 3.5 m. Calculate (i) the position, and (ii) the size of image relative to the size of the truck. What will be the nature of the image ? 3
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17. (a) Draw a ray diagram to show passage of two rays of light through a rectangular slab of glass, when the angle of incidence is zero in one case and a little less than 90° in the other case. (b) Prove that if a ray enters a rectangular glass slab obliquely and emerges from the opposite face, the emergent ray will be parallel to the incident ray.
OR
(a) State Snell’s law of refraction of light.
(b) A transparent medium A floats on another transparent medium B. When a ray of light travels obliquely from A into B the reflected ray bends away from the normal. Which of the media A and B is optically denser and why ? 3
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18. Name an important ore of aluminium. What are the impurities associated with it? How is pure aluminium obtained from this ore ? Draw a labelled diagram of the plant.
OR
(a) What method for concentration of ore is preferred in each of the following cases and why ?
(i) The ore has higher density particles interspersed with a large bulk of low density impurities. (ii) The ore consists of copper sulphide intermixed with clay particles.
(b) Give an example of amalgams. 5
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19. (a) With the help of a labelled ray diagram show how the image is formed in an astronomical telescope in normal adjustment. Write formulae for
(i) calculating the magnification by the telescope. (ii) finding the length of the tube required for the telescope.
(b) The objective of an astronomical telescope has a focal length of 2.0 m and its eyepiece has a focal length of 0.5 cm. When the telescope is in normal adjustment, find
(i) magnification by the telescope. (ii) the length of the telescope. 5
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20. Name any three forms of energy of the oceans which can be converted into usable energy forms. Describe how it is done in each case. What is the likelihood of their use on a large scale ?
OR
What are (i) solar concentrators and (ii) solar cell panels ? How are they an improvement on simple devices ? Why is it that solar cell panels are costly ? 5
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Section - B
21. State one point of difference between metacentric chromosomes and telocentric chromosomes. 1
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22. Which hormone is responsible for the development of moustache and beard in men ? 1
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23. In terms of evolution, what is the significance of homology between a human hand and awing of a bird ? 2
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24. Draw a labelled diagram of the human urinary system. 2
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25. How can air pollution lead to :
(i) skin cancer in man ? (ii) melting of ice cap of earth ? 2
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26. What is the difference between sensory and motor neutrons ? Which parts of human brain are responsible for auditory reception and sensation of smell ?
OR
What is the importance of the following processes occurring during photosynthesis in plants ? (i) Emission of electrons from chlorophyll. (ii) Photolysis of water. 3
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27. Name any two sexually transmitted diseases (STDs). How do these infectious diseases spread from one person to another ? Give two symptoms of STDs. 3
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28. (i) What does the abbreviation UASB stand for ?
(ii) Explain the process of sewage treatment after it has passed through UASB. 3
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29. Distinguish between aerobic and anaerobic respiration in terms of end-products and energy released. Why do smokers develop an over strained heart ? 3
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30. (i) State two structural differences between an artery and a vein.
(ii) Name a non nucleated cell present in human blood and state one function of this ceil.
(iii) Draw a labelled diagram of human heart. 5
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