CBSE Board Class 10 Science Previous Year Question Papers 2007

CBSE Board Previous Year Question Papers 2007 for Class 10 Science

Time allowed : 3 hours
Maximum Marks: 80
General Instructions :
(i) The question paper comprises of two sections, A and B. You are to
attempt both the sections.
(ii) All questions are compulsory.
(iii) There is no overall choice. However, internal choice has been
provided in all the three questions of five marks category. Only one
option in such questions is to be attempted.
(iv) All questions of Section A and all questions of Section B are to be
attempted separately.
(v) Questions number 1 to 4 in Section A are one mark questions.
These are to be answered in one word or one sentence.
(vi) Questions number 5 to 13 in Section A are two mark questions.
These are to be answered in about 30 words each.
(vii) Questions number 14 to 22 in Section A are three mark questions.
These are to be answered in about 50 words each.
(viii) Questions number 23 to 25 in Section A are five mark questions.
These are to be answered in about 70 words each.
(ix) Questions number 26 to 41 in Section B are multiple choice
questions based on practical skills. Each question is a one mark
question. You are to select one most appropriate response out of the
four provided to you.

1. Draw the structure for ethanoic acid molecule, CH3COOH. 1

2. Give an example of" a phenomenon where Tyndall effect can be
observed. 1

3. What is meant by biological magnification ? 1

4. Give an example to illustrate that indiscriminate use of pesticides may
result in the degradation of the environment. 1

5. How does the valency of elements vary (i) in going down a group, and
(ii) in going from left to right in a period of the periodic table ? 2

6. In the modern periodic table, the element Calcium (atomic number =
20) is surrounded by elements with atomic numbers 12, 19, 21 and 38.
Which of these elements has physical and chemical properties
resembling those of Calcium and why? 2,

7. State any four characteristics of the image of an object formed by a
plane mirror. 2

8. Draw a ray diagram to show the refraction of light through a glass
prism. Mark on it (a) the incident ray, (b) the emergent ray and (c) the
angle of deviation. 2

9. Expl~in with the help of a diagram, how we are able to observe the
sunrise about two minutes before the sun gets above the horizon.

10. List any, four reasons for vegetative propagation being practised in the
growth of some type of plants. '

11. Describe the role of fallopian tubes in the female reproductive system.

12. List any four disadvantages of using fossil fuels for the production of

13. Give two examples each of the following :
(i) Renewable sources of energy
(ii) Non-renewable sources of energy

14. Write chemical equations for what happens when
(i) sodium metal is added to ethanoic acid.
(ii) solid sodium carbonate is added to ethanoic acid.
(iii) ethanoic acid reacts with a dilute solution of sodium hydroxide.

15. The atomic number of an element'is 16. Predict
(i) the number of valence electrons in its atom
(ii) its valency
(iii) its group number
(iv) whether it is a metal or a non-metal
(v) the nature of oxide formed by it
(vi) the formula of its chloride 3

16. An object is placed between infinity and the pole of a convex mirror.
Draw a ray diagram and also state the position, the relative size and
.the nature. of the image formed. 3

17. What is the principle of reversibility of light? Show that the incident
ray of light is parallel to the emergent ray of light 'Yhen light falls
obliquely on a side of a rectangular glass slab. 3

18. What eye defect is myopia ? Describe with a neat diagram how this
defect of vision can be corrected by using a suitable lens. 3

19. What does HIV stand for? Is AIDS an infectious disease? List any
four modes of spreading AIDS. 3

20. Describe any three ways in which individuals with· a particular trait
may increase in population. 3

21. State the evidence we have for the origin of life from inanimate matter. 3

22. What are fossils? What do they tell us about the process of evolution? 3

23. (a) State two properties of carbon which lead to a very large number
of carbon compounds.
(b) Why does micelle formation take place when soap is added to
water? Why are micelles not formed when soap is added to
ethanol? 5
Explain isomerism. State any four characteristics of isomers. Draw
the structures of possible isomers of butane, C4HlO. 5

24. (a) What is meant by 'power of a lens' ?
State and define the S.l. unit of power of a lens.
A convex lens of focal length 25 cm and a concave lens of focal
length 10 cm are placed in close contact with each other.
Calculate the lens power of this combination.

5(a) Draw a ray diagram to show the formation of image of an object
placed between infinity and the optical centre of a concave lens.
(b) A concave lens of focal length 15 em forms an image 10 em from
the lens.
(i) the distance of the object from the lens
(ii) the magnification for the image formed
(iii) the nature of the image formed

25. With the help of suitable diagrams, explain the varIOUS steps of
budding in Hydra. 5
What is binary fission in organisms ? With the help of suitable ?iagrams, describe the mode of reproduction in Amoeba. 5

26. To find the focal length of a concave mirror, Sita should choose which
one of the following set-ups ? 1
(A) A mirror holder and a screen holder
(B) A screen holder and a scale
(C) A mirror holder, a screen holder and a scale
(D) A screen, a mirror, holders for them and a scale

27. By using a convex lens, a student obtained a sharp image of his
class-room window grill on a screen. In which direction should he move
the lens to focus a distant tree instead of the grill ? 1
(A) Towards the screen
(B) Away from the screen
(C) Very far away from the screen
(D) Behind the screen

28. To determine the focal length of a convex lens by obtaining a sharp
image of a distant object, the following steps were suggested which are
not in proper sequence :
I. Hold the lens between the object and the screen.
II. Adjust the position of the lens to form a sharp image.
III. Select a suitable distant object.
IV. Measure the distance between the lens and the screen.
The correct sequence of steps to determine the focal length of the
lens is 1
(A) III, I, II, IV (B) III, I, IV; II
(C) III, IV, II, I (D) I, Ii, III, IV

29. In these diagrams, the angle of refraction r has been correctly marked
in which diagram ? 1
(A) I (B) II
(C) III (D) IV

30. For a ray of light passing through a glass slab the lateral displacement was correctly measured as 1
(A) AB (B) PQ
(C) CD (D) PR

31. Iron nails were dipped in an aqueous solution of copper sulphate. After
about 30 minutes, it. was observed that the colour of the solution
changed from 1
(A) colourless to light green.
(B) blue to light green.
(C) blue to colourless.
(D) green to blue.

32. A cleaned aluminium foil was placed in an aqueous solution of zinc
sulphate. When the aluminium foil was taken out of the zinc sulphate
solution after 15 minutes, its surface was found to be coated with a
silvery grey deposit. From the above observation it can be concluded
(A) aluminium is more r~active than zinc.
(B) zinc is more reactive than aluminium.
(C) zinc and aluminium both are equally reactive.
(D) zinc and aluminium both are non-reactive.

33. Vapours of acetic acid smell
(A) pungent like vinegar.
(B) sweet like rose.
(C) suffocating like sulphur dioxide.
(D) odourless like water.

34. Acetic acid reacts with solid sodium hydrogen carbonate
(A) slowly forming no gas.
(B) . vigorously with effervescence.
(C) slowly without effervescence.
(D) vigorously without gas formation.

35. A student added acetic acid to test tubes I, II, III and IV containing
the labelled substances and then brought a burning splinter near the
mouth of each test tube.
II NaGl