CBSE Science Practice Paper Set VII

Section - A

1. What is meant by endothermic process ? Give one example. 1


2. Name any two elements used for fabrication of solar cells. 1


3. Who proposed the Big-Bang theory of the origin of Universe. 1


4. What are strong acids ? Give one example. 1


5. What is the magnification for a plane mirror ? 1


6. What is formula of washing soda ? 2


7. State Coulomb’s law of electric charges ? 2


8. What is INSAT ? What are its objectives ?

OR

Give two major objectives of ISRO ? 2


9. Calculate pH of 0.01 M HC1 if it is fully dissociated. 2


10. A space shuttle utilises 100 Kg of liquid hydrogen during a flight. If the calorific value of hydrogen is 150 kJ/g, how much energy did it consume ? 2


11. What are communication satellites ? Why don’t we use moon as a communication satellite ? 3


12. What is meant by quenching of glass ? What type of glass do we get by this process ?


OR

Which one of the following reaction equations represents combustion of carbon and why ? Give another example of combustion reaction.
(i) 2C + O2 ——-> 2CO
(ii) C + O2 ——> CO2
(iii) 3C + O2 —-> 2CO + CO2. 3


13. What is electro-plating ? Explain the process with a diagram. Give two real life applications of the process. 3


14. What is the significance of Oersted’s experiment ? Draw the magnetic field created by a long conductor carrying current. 3


15. How will you prepare hydrogen gas in laboratory ? Draw a neat and labelled diagram and write chemical reaction involved. How will you test the presence of hydrogen gas ? 3


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

OR

Fission ol one uranium nuclei gives 200 MeV of energy. To produce 100 KW power for a day, how much of uranium is required ?


17. Complete the following reaction and write the names of reactants and products.



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.

OR

What is the difference between soaps and detergents ? Give one example of each. Give advantages and disadvantage of soaps and detergents. 5


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 ?

OR

With a neat diagram, explain how a solar water heater works. Mention two limitations in the use of solar energy. 5


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

Section - B

21. How many types of chromosomes are there in the human cells ? 1


22. Name the functional unit of lungs. 1


23. State two ways for the disposal of radioactive wastes. 1


24. Give the difference between exocrine and endocrine glands. 2


25. What is human karyotype ? 2


26. Define unisexual flower and bisexual flower. Give one example of each. 3


27. What is eutrophication ? Mention its harmful effects. 3


28. What is blood group ? What is its importance in the body ? 3


29. Write the difference between hormones and enzymes. 3


30. Draw and label the parts of the human excretory system. 5