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CBSE X
Set -3
SCIENCE PAPER 2012

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

 Section A Section B Section C Section D

### Question 1

1. Write the name and formula of the first member of the carbon compounds having functional group âˆ’ CHO.

### Question 2

2. State one role of ciliary muscles in the human eye.

### Question 3

3. Write the name and formula of a molecule made up of three atoms of oxygen.

### Question 4

4. Name two decomposers operating in our ecosystem.

### Question 27

27. The following figure illustrates binary fission in Amoeba in an incorrect sequence.

The correct sequence is

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

### Question 28

28. From the following diagrams, select the correct ones showing stages of binary fission in amoeba:

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

### Question 29

29. Following diagrams were drawn by different student on having seen prepared slides of budding in yeast.

Correct diagrams are

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

### Question 30

30. In which of the following figures is budding not shown?

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

### Question 31

31. A student weighed some raisins and recorded the weight as â€˜xâ€™. She then soaked the raisins in distilled water. After about 2 hours she removed the raisins, wiped them dry and weighed again and recorded that as â€˜yâ€™. The percentage of water absorbed by raisins may be determined using the relationship:

Options:
1. $\frac{yâˆ’x}{y}×100$
2. $\frac{yâˆ’x}{x}×100$
3. $\frac{yâˆ’x}{x}×\frac{1}{100}$
4. (yâˆ’x)×100

### Question 32

32. In the experiment for determining the percentage of water absorbed by raisins, we do the final weighing of the raisins after keeping them dipped in water for about one hour. For the accuracy of the result, the extra water from the surface of the soaked raisins is removed by

Options:
1. Rubbing with cotton cloth
2. Hot air blower
3. Dry cotton wool
4. Filter paper

### Question 33

33. On adding 2 mL acetic acid to 2 mL of water in a test tube, it was observed that

Options:
1. a clear and transparent solution is formed
2. a white precipitate is formed almost immediately
3. two separate layers were formed
4. a colourless and odourless gas is evolved

### Question 34

34. On adding acetic acid to sodium hydrogen carbonate in a test tube, a student observes

Options:
1. No reaction
2. A colourless gas with pungent smell
3. Bubbles of a colourless and odourless gas
4. A strong smell of vinegar

### Question 35

35. Which one of the following are the correct observations about acetic acid?

Options:
1. It turns blue litmus red and smells like vinegar
2. It turns blue litmus red and smells like burning sulphur
3. It turns red litmus blue and smells like vinegar
4. It turns red litmus blue and has a fruity smell

### Question 36

36. The aqueous solutions of copper sulphate and zinc sulphate appear

Options:
1. Blue and green respectively
2. Green and colourless respectively
3. Blue and brown respectively
4. Blue and colourless respectively.

### Question 37

37. Solutions of copper sulphate, iron sulphate and zinc sulphate are prepared and marked I, II and III respectively. Few pieces of aluminum are added to each solutions. After some time a change will be observe in.

Options:
1. I and II
2. II and III
3. III and I
4. All the three

### Question 38

38. Four students showed the following traces of the path of a ray of light passing through a rectangular glass slab.

The trace most likely to be correct is that of student

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

### Question 39

39. While performing the experiment on tracing the path of a ray of light through a rectangular glass slab, in which of the following experimental set-ups is a student likely to get best results? P1 and P2 are the positions of pins fixed by him.

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

### Question 40

40. If you are to determine the focal length of a convex lens, you should have

Options:
1. a convex lens and a screen
2. a convex lens and a lens holder
3. a lens holder, a screen holder and a scale
4. a convex lens, a screen, holder for them and a scale

### Question 41

41. A student obtained a sharp inverted image of a distant tree on a screen placed in front of the concave mirror. He then removed the screen and tried to look into the mirror. He would now see

Options:
1. a very blurred image on the wall opposite to the mirror
2. an erect and magnified image of the tree in the mirror
3. no image as the screen has been removed
4. a highly diminished inverted image of the tree at the focus of the mirror

### Question 42

42. A student has to determine the focal length of a concave mirror by obtaining the image of a distant object on a screen. For getting best result he should focus

Options:
1. a distant tree or an electric pole
2. a well-illuminated distant building
3. well-lit grills of the nearest window
4. a burning candle placed at the distant edge of the laboratory table