CBSE Science Sample Paper Set I

Describe
1. Name the mirror which always forms a virtual image ?

2. How is slurry left over after generation of biogas in gobar gas plant used ?

3. Write a condition necessary for current flow.

4. Define rate of reaction.

5. How much solar energy is incident on India’s surface (on an average) ?

6. Which one of the metals in the following group are : (a) most reactive and (b) least reactive Au, Na, Cu, Ca.

7. How do we see colours ?

8. Define ‘combustion’. Write the conditions necessary for combustion to take place.

9. What is energy crisis ? How do we overcome the same ?

OR

What are the advantages and drawbacks in the use of wind energy ?

10. When two equal resistors are placed in parallel, the equivalent resistance is 5 Q. When they are placed in series, what will be the equivalent resistance ?

11. State two reasons for counting sulphur among the non-metals. Which properties of sulphur make it possible to bring sulphur from deep mine to the surface of the Earth by the Frasch process and to purify it by sublimation of liquid sulphur ?

12. What are Geostationary satellites ? In what way they are useful to mankind ?
OR 
Explain why nuclear fusion is better than nuclear fission ?

13. The heat produced on complete combustion of 10 g of fuel could raise the temperature of 2 Kg of water from 20° to 70°C. Calculate the calorific value of the fuel, if the specific heat of water is 4.2 J/g °C.

OR

How much energy will 1 Kg mass of wood yield on complete combustion if its calorific value is 15 kJ/g.

14. Draw a neat diagram of a compound microscope and explain the nature of image formed. Also write the relation for magnification.

15. What are magnetic field lines ? List four characters of these lines.

16. An organic compound ‘A’ has molecular formula (CJH.OA It reacts with sodium carbonate to produce a gas and salt, the gas turns lime water milky.
(a) What is the functional group in the compound ‘A’ ?
(b) Write its structural formula.
(c) What is IUPAC name of ‘A’ ?
(d) Give chemical equations for reaction involved with sodium carbonate and the gas evolved with lime water.

17. What are constellations ? Name any two constellations visible in (i) Spring and (ii) Autumn. Draw the shape of any one in each season.

18. What is total internal reflection ? Give the conditions needed for the same. Give two applications. Critical angle for glass air interface is 41 °. Write the refractive index and express whether T.I.R. takes place or not when incident angle is 45°.

19. A gas is obtained by heating ammonium chloride with slaked lime. It can also be obtained by reaction of element ‘X’ with another element ‘Y! in presence of catalyst. The gas gives dense white fumes with hydrogen chloride and turns red litmus blue. Identity the gas and write equations for all 
the chemical reactions involved.

OR

How is steel manufactured by Bassemer process ? Give composition and uses of (i) Stainless steel, (ii) Manganese steel.

20. Define fermentation. How is ethanol manufactured by (i) fermentation, (ii) ethene ?
Give two physical and two chemical properties of ethanol

Section - B
21. What is the mode of nutrition in fungi ?

22. Define reflex action.

23. ‘Nutrition is necessary for all organisms’. Why ?

24. Write about the proteins present in plasma.

25. What is phytohormone ? Name two phytohormones.

26. Explain double fertilisation with a diagram of fertilisation in plants.

27. ‘Ontogeny repeats phylogeny’ ? Explain the meaning of this statement.

28. How do plants obtain food ? What are the two phases of photosynthesis ?

29. Describe with labelled diagram the alimentary canal of man.

30. What do you mean by soil pollution ? What are the adverse effect of them ?

OR

What is soil erosion ? What are its causes and effects ? How can it be checked ?
Answer : e the digestion of proteins through the various regions of the alimentary canal. Also mention the end products of protein digestion absorbed into the body ? 5

31. Determine the pH of the acidic solution formed when 0.02 mol of HC1 is added to enough water to make the final volume 2.0 L.

32. Draw a neat diagram of an astronomical telescope and write the nature of image formed. Write the relation for magnification and the length of telescope under normal adjustment. 3