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CBSE X
Set -3
SCIENCE PAPER 2011

Time allowed: 180 minutes; Maximum Marks: 90

General Instructions:
1)  All questions are compulsory.
2) The question paper consists of 42 questions divided into 4 sections A, B, C and D. Section A comprises questions of 01 mark each, Section B comprises questions of 02 marks each, Section C comprises questions of 03 marks each and Section D comprises questions of 05 marks each.
3)  All questions in Section A are to be answered in one word, one sentence or as per the exact requirement of the question.
4) There is no overall choice. However, internal choice has been provided wherever necessary.You have to attempt only one of the alternatives in all such questions.
5)  In question on construction, drawing should be near and exactly as per the given measurements.
6) Use of calculators is not permitted.

SECTION A

Question 1

1. What are the various steps in a food chain called?

Question 2

2. What is the important function of presence of ozone in earth’s atmosphere?

Question 3

3. Write the electron dot structure of ethane molecule, C2H6.

Question 4

4. What makes the earth’s atmosphere a heterogeneous mixture?

Question 27

27. A student was given two permanent slides, one of binary fission in amoeba and other of budding in yeast. He was asked to identify any one difference in the nucleus of the two. One such difference he identified correctly was

Options:
1. Presence of one nucleus in amoeba, two in yeast cell and one in bud.
2. Presence of two nuclei in centrally constricted amoeba, one in yeast cell and one in its bud.
3. Presence of two distant nuclei in amoeba, one in yeast cell and two in bud.
4. Presence of a single nucleus each in amoeba, yeast cell and its attached bud.

Question 28

28. Binary fission is observed in which one of the following figures?

Options:
1. A
2. B
3. C
4. D

Question 29

29. To determine the percentage of water absorbed by raisins, raisins are soaked in water for:

Options:
1. 30 seconds
2. 10 minutes
3. 2 to 3 hours
4. 24 hours

Question 30

30. Raisins are wiped off gently before final weighing with help of

Options:
1. a filter paper
2. a cotton piece
3. a cloth piece
4. a polythene piece

Question 31

31. The step(s) necessary for determining the percentage of water absorbed by raisins is/are:

Options:
1. Raisins should be completely immersed in water
2. Raisins should be soaked in water for sufficient time
3. Gently wipe dry the soaked raisins
4. All of the above steps.

Question 32

32.

Rahim recorded the following sets of observations while tracing the path of a ray of light passing through a rectangular glass slab for different angles of incidence.

The correct observation is recorded at serial number:

Options:
1. I
2. II
3. III
4. IV

Question 33

33.

Four students A, B, C and D traced the paths of incident ray and the emergent ray by fixing pins P and Q for incident ray and pins R and S for emergent ray for a ray of light passing through a glass slab.

The correct emergent ray was traced by the student:

Options:
1. A
2. B
3. C
4. D

Question 34

34. Mohan obtained a sharp inverted image of a distant tree on the screen placed behind the lens. He then moved the screen and tried to look through the lens in the direction of the object. He would see:

Options:
1. A blurred image on the wall of the laboratory.
2. An erect image of the tree on the lens.
3. No image as the screen has been removed
4. An inverted image of the tree at the focus of the lens.

Question 35

35. For finding the focal length of a convex lens by obtaining the image of a distant object, one should use as the object.

Options:
1. A well lit distant tree
2. Window grill in the class room
3. Any distant tree
4. A lighted candle kept at the other end of the table.

Question 36

36. To find the focal length of a concave mirror Rahul focuses a distant object with this mirror. The chosen object should be:

Options:
1. A tree
2. A building
3. A window
4. The sun

Question 37

37. The colour of an aqueous solution of zinc sulphate as observed in the laboratory is:

Options:
1. Green
2. Yellow
3. Blue
4. Colourless

Question 38

38. To show that zinc is a more active metal than copper, the correct procedure is to:

Options:
1. Add dilute nitric acid on strips of both the metals.
2. Observe transmission of heat through strips of zinc and copper.
3. Prepare solution of zinc sulphate and hang strip of copper into it.
4. Prepare solution of copper sulphate and hang strip of zinc into it.

Question 39

39. Acetic acid smells like:

Options:
1. A banana
2. Vinegar
3. An orange
4. A lemon

Question 40

40. Acetic acid solution turns:

Options:
1. Blue litmus red
2. Red litmus blue
3. Blue litmus colourless
4. Red litmus colourless

Question 41

41. On adding NaHCO3 to acetic acid, a gas is evolved which turns lime water milky due to the formation of:

Options:
1. Calcium bicarbonate
2. Calcium hydroxide
3. Calcium carbonate
4. Calcium acetate

Question 42

42. A yeast cell in which budding occurs was seen to have:

Options:
1. one bud cell
2. two bud cell
3. three bud cell
4. a chain of bud cells

SECTION B

Question 5

5.

List any four characteristics of a good fuel.