CBSE Science Practice Paper Set VIII

Section - A

1. Name any two non-renewable sources of energy. 1
 

2. Write any two examples of harmful radiations emitted by the nuclear wastes ? 1
 

3. What will happen to white light on entering a prism ? 1
 

4. Wright Me equation for laboratory preparation of hydrogen gas. 1
 

5. Win-it a wire of resistance R, length / is made into a circle, what is the resistance between two points at the end of its diameter ?

OR

Why do we use semiconductors more in electronic devices. 1
 

6. How can we use solar energy to overcome energy crisis ? 2
 

7. Calculate pH of the solution when hydrogen ion concentration is 1.0 x 10-6 M. 2
 

8. What is a wind mill ? Give two advantages and disadvantages of wind mill. 2
 

9. What is meant by annealing of glass ? What type of glass do we get by this process ? 2
 

10. If three 60 W bulbs are used for 6 hours a day and a tube light of 40 W is used for 4 hours, calculate the cost of electricity in a month of 30 days, if the cost of 1 unit is Rs. 2.50. 2
 

11. Write two examples of ‘fossil fuel’. Why are they preferred over wood ? 3
 

12. Draw a labelled diagram of Alternating current generator, 3
 

13. What is total internal reflection ? Relate the angle of incidence and the refractive index for total internal reflection. Write the conditions necessary for total internal reflection. 3
 

14. What are constituents of bronze ? Write its two main uses. Name the common constituent of brass, bronze and german silver.

OR

What type of mixtures are separated by fractional distillation ? Name the fraction of crude oil whose boiling point is more than 3500C. Where is it mostly used as a fuel ? 3
 

15. What is the meaning of power of a lens ? When a convex lens of focal length 10 cm and concave lens of focal length 20 cm are placed in contact, find the equivalent focal length and power.

OR

A convex lens of 10 cm focal length and a concave lens of 20 cm focal length are kept in contact, how does the combination behave. Give reason. 3
 16. What are the factors affecting the heat produced in a wire ? Define electric power. Relate electrical unit of electricity to joule. 3
 

17. How are esters formed ? Write chemical equation for one such reaction. Write one use of esters. 3
 

18. What are satellites ? Mention the types of orbits used to place them. How are they launched ? Explain,5
 

19. With a labelled ray diagram explain how an Astronomical telescope works. Also give its magnification. 5
 

20. Name the- chief ore of iron. How will you extract iron from this ore ? Write all the reactions involved in blast furnace and draw its neat and labelled diagram. How Ls iron refined ?

OR

Name chief ore of aluminium. How can we extract it from this ore ? Give two alloys of aluminium, their composition and uses. 5
 


Section - B

21. What is meant by photochemical reaction ? 1
 

22. Give one example each of binary fission and multiple fission. 1
 

23. Define the terms: (a) nerve impulse, (b) axon. 1
 

24. Explain the terms : (a) acid rain (b) ozone depletion. 2
 

25. What are the two kinds of xylem elements ? 2
 

26. How does heterotrophic organisms depend upon autotrophic organisms ? 3
 

27. What is vegetative propagation ? Classify giving suitable examples. 3
 

28. Who is the ‘founder of genetics1 ? How has the term ‘factor’ been modified today ? What was Mendel’s working material ? Briefly summarise his work. 3
 

29. Mention the three main characteristic features of potable water. 3
 

30. Write briefly about stages in photosynthesis process;

OR

Explain with a diagrammatic representation the mechanism of gaseous exchange between tissues and blood. 5