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CBSE X
Set -2
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. Name the functional group present in each of the following compounds:

(i) HCOOH

(ii) C2H5CHO

### Question 2

2. The sky appears dark instead of blue to an astronaut. State its reason.

### Question 3

3. Depletion of ozone in the ozone layer is a cause for our worry. Why?

### Question 4

4. Name two decomposers operating in our ecosystem.

### Question 27

27. A student traces the path of a ray of white light through a rectangular glass slab and marks, the angles of incidence (âˆ i) , refraction (âˆ r) and emergence (âˆ e) as shown. Which angle or angles has he not marked correctly?

Options:
1. âˆ i only
2. âˆ i and âˆ r
3. âˆ i and âˆ e
4. âˆ r and âˆ e

### Question 28

28. While tracing the path of a ray of light passing through a rectangular glass slab a student tabulated his observations as given below:

 S.No âˆ i âˆ r âˆ e I 60Â° 40Â° 61Â° II 50Â° 36Â° 51Â° III 40Â° 28Â° 39Â° IV 30Â° 20Â° 31Â°

The correct observations is:

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

### Question 29

29. To determine focal length of a concave mirror a student obtains the image of a well lit distant object on a screen. To determine the focal length of the given concave mirror he needs to measure the distance between:

Options:
1. mirror and the object
2. mirror and the screen
3. screen and the object
4. screen and the object and also mirror and the screen

### Question 30

30. A student obtained a sharp image of the grills of a window on a screen using a concave mirror. His teacher remarked that for getting better results a well lit distant object (preferably the sun) should be focussed on the screen. What should be done for this purpose?

Options:
1. Move the screen slightly away from the mirror
2. Move the mirror slightly towards the screen
3. Move the screen and the mirror away from the object
4. Move the screen and the mirror towards the object

### Question 31

31. To determine the focal length of a convex lens by obtaining a sharp image of a distant object we generally follow the following steps which are not in proper sequence.

(a) Hold the lens between the object and the screen

(b) Measure the distance between the lens and the screen

(c) Select a well lit distant object

(d) Place a screen opposite to the object on the lab table

(e) Adjust the position of the lens to form a sharp image

The correct sequence of these steps is:

Options:
1. c, a, d, e, b
2. c, d, a, e, b
3. c, d, e, a, b
4. c, a, e, d, b

### Question 32

32. Dry raisins were soaked in water for 2 hours, to determine the percentage of water absorbed by raisins. Before final weighing of swollen raisins, the extra water left on the surface of soaked raisins was removed by:

Options:
1. gently rubbing with cotton cloth
2. hot air blower
3. dry cotton wool
4. filter paper

### Question 33

33. While performing the experiment with raisins to determine the percentage of water absorbed by them, a student made following measurements:

Mass of water in the beaker = 40 g

Mass of raisins before soaking = 5 g

Mass of raisins after soaking for 2 hours = 8 g

Mass of water left in the beaker after the experiment = 35 g

The percentage of water absorbed by raisins is:

Options:
1. $\frac{40gâˆ’35g}{35g}\text{}\text{}×100$
2. $\frac{40gâˆ’35g}{40g}×100$
3. $\frac{8gâˆ’5g}{8g}×100$
4. $\frac{8gâˆ’5g}{5g}×100$

### Question 34

34. After observing the prepared slides of binary fission in amoeba and budding in yeast following observations were reported:

(A) Single cells of amoeba and yeast were undergoing binary fission and budding respectively.

(B) Cytokinesis was observed in the yeast cell.

(C) Elongated nucleus was dividing to form two daughter nuclei in amoeba.

(D) A chain of buds were observed due to reproduction in amoeba.

The correct observation(s) is/are:

Options:
1. A and C
2. B only
3. C and D
4. D, A and C

### Question 35

35. A student after viewing a prepared slide illustrates the budding in yeast in the following order which is not correct:

Options:
1. b, c, d, e, a
2. b, e, d, c, a
3. b, d, e, c, a
4. b, d, c, e, a

### Question 36

36. A student has to observe a permanent slide of binary fission in amoeba. Find the correct sequence of steps given below for focusing the object under a microscope.

(a) Place the slide on the stage, look through the eye-piece and adjust the mirror to get proper illumination.

(b) Focus the slide sharp using fine adjustment screw

(c) Look through the eye-piece and raise the objective lens using coarse adjustment screw till the object is focused.

(d) Look through the eye-piece and move the slide till the object is visible.

Options:
1. d, c, b, a
2. a, b, d, c
3. a, d, c, b
4. a, c, d, b

### Question 37

37. After viewing different slides, a student draws following diagrams. Select the one which depicts binary fission in amoeba:

Options:
1. a
2. b
3. c
4. d

### Question 38

38. Which of the following observations is true about dilute solution of acetic acid?

Options:
1. It smells like vinegar and turns red litmus blue
2. It smells like onion and turns blue litmus red
3. It smells like orange and turns red litmus blue
4. It smells like vinegar and turns blue litmus red

### Question 39

39. A student takes Na2CO3 powder in a test tube and pours some drops of acetic acid over it. He observes

Options:
1. No reaction in the test tube
2. Colourless gas with pungent smell
3. Bubbles of a colourless and odourless gas
4. White fumes with smell of vinegar

### Question 40

40. A student adds 4 mL of acetic acid to a test tube containing 4 mL of distilled water. He then shakes the test tube and leaves it to settle. After about 10 minutes he observes:

Options:
1. A layer of water over the layer of acetic acid
2. A layer of acetic acid over the layer of water
3. A precipitate settling at the bottom of the test tube
4. A clear colourless solution

### Question 41

41. The colours of aqueous solutions of CuSO4 and FeSO4 as observed in the laboratory are:

Options:
1. Pale green and light blue respectively
2. Light blue and dark green respectively
3. Dark blue and dark green respectively
4. Dark blue and pale green respectively

### Question 42

42. A student prepared an aqueous solution of CuSO4 in beaker X and an aqueous solution of FeSO4 in beaker Y. He then dropped some iron pieces in beaker X and some zinc pieces in beaker Y. After about 10 hours he observed that the solutions in X and Y respectively appear:

Options:
1. Blue and green
2. Colourless and pale green
3. Colourless and light blue
4. Greenish and colourless

 Section A Section B Section C Section D
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