CBSE Science Practice Paper Set IX

Section – A

1. What is the density of mass of a typical white dwarf star ? 1
 

2. What are enzymes ? Give an example. 1
 

3. Write chemical name and formula of baking soda, 1
 

4. Name the orbit of the satellites that help in satellite communication. 1
 

5, Give chemical equation for reaction of acetone with HCN. 1
 

6. Write the significance of Faraday’s Constant. 2
 

7. Name some devices used to tap solar energy. Give two limitations in its use. 2
 

8. Calculate pH of 0.01 M NaOH solution assuming it to be fully ionised in aqueous solution. 2
 

9, A family consumes 14.5 Kg of LPG in 28 days. Calculate the average energy consumed per day if the calorific value of LPG is 55 kJ/g. 2
 

10. A satellite orbits a planet in a radins ‘r’ Derive a relation for the velocity of satellite in the orbit. 2
 

11. Complete the following reactions :



 

12. A star of mass 100 times that of the sun has come to red giant phase. Explain the next two phases in its life. 3
 

13. Write structural formula of ethanoic acid. What is common name of pure ethanoic acid ? How will you prepare it from methanol ? Give chemical reaction involved and one use of ethanoic acid.

OR

{a) What is gypsum ? What happens when gypsum is heated to 373 K ?
(b) Define ‘calorific value of a fuel’. Amongst the following fuels, which one has the highest calorific value ?
C2H5OH,CH4,C2H2.
 

14. Two resistors 2Ω and 5Ω are connected as shown in the circuit.
Find (i) current drawn from cell, 



(ii) Heat produced in each resistor in 2 minutes.

OR

If 2Ω and 5Ω resistors are connected in parallel to a 10 V cell, find (i) current in each resistor, (ii) ratio of heat produced in them. 3
 

15. Write the reaction that takes place in a nuclear reactor. What is meant by enrichment of fuel ? When is a nuclear reactor said to have become critical ? 3
 

16. What happens when
(i) Methanal is oxidised by ammonical silver nitrate solution. (ii) Cumene is treated with air (iii) Ethene undergoes polymerisation. Write the chemical reactions involved. 3
 

17. (i) Derive the formula 1/f = 1/v – 1/u for a lens.

(ii) Define magnification and relate it to/and it. 3
 

18. What is solenoid ? Compare it with a bar magnet. How can we identify its field direction ? 5
 

19. Define allolropy. Give three allotropes of sulphur. Explain action of heal on sulphur. What happens when (0 carbon is heated with sulphur, (ii) Hydrogen gas is passed through boiling sulphur ?


OR

How will you manufacture sulphuric acid by contact process ? Explain the process giving chemical equations. Give two physical and two chemical properties of H2SO4. 5
 

20. Draw a neat labelled diagram of a compound microscope and explain about the magnification of each lens used. 5
 


Section - B

21. Name the transport system in plants and animals. 1
 

22. Name the excretory organs of earthworm. 1
 

23. How is menarche different from menopause ? 1
 

24. Whose theory influenced Darwin ? What did Darwin fail to explain ? 2
 

25. Where do you find chiorophyil in the plant body ? What is the site of chlorophyll ?


OR

Justify transpiration as a force promoting the ascent of sap. 2
 

26. Differentiate between male and female reproductive system. 3
 

27. What is the main difference between sympathetic system and parasympathetic system ? 3
 

28. What is emphysema ? Give its symptoms. 3
 

29. Draw the structure of a neuron and label all its parts. 3
 

30. What do you mean by conservation ? What are the methods for conservation of the environment ? State why. the environmental law are to be enforced ?


OR

(i) Who provided the evidence of DNA as a genetic material ? Mention about the components of DNA.
(ii) Give a detailed description of the structure of a DNA molecule. 2+3