CBSE Science Practice Paper Set III

1. Relate refractive index with the speed of light in the medium, 1


2. Name the elements other than carbon that constitute carbohydrates. 1


3. What is Faraday’s constant ? 1


4. What are the units of rate of reaction. 1


5. Give IUPAC name of H-C-H 1


6. What are solar concentrators ? Give the usual shape of such concentrators. 2


7. If an object is at 10 cm from a convex lens of focal length 15 cm, find (i) position {ii) nature of image formed. 2


8. Name two places of one country where fields of natural gas are found. Why is it called a clean fuel ? Give two reasons. 2


9. When two lenses of focal length 20 cm and - 30 cm are placed in contact. Find the equivalent. (i) Focal length (ii) Power 2


10. Calculate the pH of the solution when hydrogen ion concentration is lxl0 -7 M. State whether the solution is acidic, basic or neutral.


OR

The pH of solution is 4. Calculate hydrogen ion concentration. State the solution is acidic, basic or neutral. 2


11. A 60 W, 220 V bulb and a 40 W, 220 V bulb are used with a supply of 220 V in series. Find the (*) Net power consumed (it) Identify the brighter of the two bulbs.
OR
A 60 W, 220 V bulb and a 25 W, 220 V bulb are to be connected to a 220 V supply. How will you connect them to get (/) maximum potential in each, («) current through each bulb. 3


12. Write chemical equations to show what happens when ;
(i) Concentrated HNO3 is poured over sulphur powder. {ii) Na2CO3.10H2O crystals are exposed to air {Hi) Manganese dioxide is heated with aluminium. 3


13. Draw a labelled diagram of an A. C. generator. Write the basic principle underlining its functioning.3


14. How does pyrcx glass differ from soda glass ? Give composition of lead crystal glass. 3


15. Explain the role of ciliary muscles, cornea and aqueous humour in helping the eye in its ability of accommodation. 3


16. How does sulphur occur in nature ? How will you extract sulphur from sulphur beds ? Draw a neat and labelled diagram and explain the principle on which its extraction is based.

What kind of materials are called thermoplastics ? Give two examples. Why are thermoplastic materials different from thermosetting materials ? 3


17. Compare the energy released during fission and fusion. Write the advantages of fusion over fission. 3


18. How will you manufacture sulphuric acid by contact process ? Write the name of catalyst. Write the chemical reactions involved. Why is SO3 not absorbed in water directly ? Give two uses of sulphuric acid. 5


19. Show the image formation and write the nature of image when object is placed (/) between O and F and (ii) beyond 2F of a convex lens whose optical centre and focus are identified as O and F.


OR

What is wind energy ? Explain how a wind mill be used to tap energy. Give two advantages and limitations of wind energy. 5


20. Define fermentation. How is ethanol manufactured by (/) fermentation, (ii) ethene ?


OR

(a) How does ethanol reacts with
(0 Na metal (ii) CH3COOH (Hi) CrO3 in acetic acid
(b) How does propanone reacts with (0 NaBH4(i/)HCN
Give chemical reactions. 5



Section - B

21. Name the part of vascular bundle through which transport of Water and mineral


22. What is endocrine gland ? 1


23. Define vestigeal organs. Give examples. 1


24. Give one example each of the following :
(a) Plant which reproduces naturally by vegetative propagation of leaf.
(b) Plant which reproduces naturally by vegetative propagation of stem. 2


25. Define pollutants. Give one example each of (a) Primary pollutant, (b) Secondary pollutant. 2


26. Explain the functions of plasma. 3


27. List the various characteristics of hormones. 3


28. Mention the various causes of soil erosion. 3


29. What are the different salivary glands present in man ? Mention their main functions. 3


30. What is AIDS ? Write the name of its causal organism, symptoms and prevention. 5