CBSE Science Practice Paper : Set VII
16. Find the energy released in the reaction (in joules)
235U + n —-> 95Mo + 139La + 2n
Given : Mass of Mo = 94.946 u, Mass of La = 138.955 u, Mass of n= 1.009u, Mass of Uranium = 235.919u
I u = 931 MeV
Fission ol one uranium nuclei gives 200 MeV of energy. To produce 100 KW power for a day, how much of uranium is required ?
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17. Complete the following reaction and write the names of reactants and products.
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18. What is meant by polymerisation ? How do addition and condensation polymer differ ? Give two example each of addition and condensation polymerisation. Give one of each polymer.
What is the difference between soaps and detergents ? Give one example of each. Give advantages and disadvantage of soaps and detergents. 5
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19. What is refraction ? Write the basic laws of refraction. What happens to the frequency, velocity and wavelength as right moves from one medium to another ? Based on the bending, how can you identify the nature of the medium ?
With a neat diagram, explain how a solar water heater works. Mention two limitations in the use of solar energy. 5
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20. What is the formula of ammonia ? Give two physical properties of ammonia. How is it manufactured by Haber’s process ? Give chemical reactions involved. 5
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21. How many types of chromosomes are there in the human cells ? 1
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22. Name the functional unit of lungs. 1
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23. State two ways for the disposal of radioactive wastes. 1
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24. Give the difference between exocrine and endocrine glands. 2
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25. What is human karyotype ? 2
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26. Define unisexual flower and bisexual flower. Give one example of each. 3
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27. What is eutrophication ? Mention its harmful effects. 3
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28. What is blood group ? What is its importance in the body ? 3
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29. Write the difference between hormones and enzymes. 3
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30. Draw and label the parts of the human excretory system. 5
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