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CBSE Guess > Papers > Question Papers > Class X > 2005 > Science > Delhi Set-III


Except for the following questions, all the remaining questions have been asked in Set 1 and Set 2.


Q. 1. A green layer is gradually formed on a copper plate left exposed to air for a week in a bathroom. What could this green substance be? 1

Q. 4. Why is tungsten metal selected for making filaments of incandescent lamp bulbs? 1

Q. 7. What is the activity series of metals? Rearrange the following metals in an increasing order of reactivity:
Aluminium, Zinc, Mercury 2

Q. 10. With respect to air the refractive index of ice is 1.31 and that of rock-salt is 1.54. Calculate the refractive index of rock-salt with respect to ice. 2

Q. 13. State the steps involved in the manu facture of oleum from sulphur. Write the chemical equations for the reactions involved. 3

Q. 17. A torch bulb is rated 3.0 V and 600 rnA. Calculate: (z) its power, (ii) its resistance and (iii) the energy consumed if it is lighted for 4 hours. 3

Q. 19. Why is pure iron not used for making permanent magnets? Name one material used for making permanent magnets. Describe how permanent magnets are made electrically. State two examples of electrical instruments made by using permanent magnets. 5


Q. 21. How are metacentric and acrocentric chromosomes different from each other in shape? 1

Q. 24. Describe any one technique of controlling gaseous pollutants of air. 2

Q. 30. Explain the following aspects of photosynthesis in plants:
(i) The role of chlorophyll
(ii) Dark reaction
(iii) Calvin-Benson cycle 5

Science 2005 Question Papers Class X