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# CBSE CLASS 10 SCIENCE SAMPLE PAPER - 1

CBSE X

Science

Sample Paper

Max. Marks: 90                                                                                                                                   Duration: 3 Hours

General Instructions:

• This paper is formatted as follows:
• The question paper contains 2 sections A and B, in which section B contains the questions based on the practical performed.
• All the questions are compulsory.
• Section A: (consists of Descriptive type of Questions only)
• Questions 1 to 3 carries 1 mark per question. Answer in one word or in one sentence.
• Questions 4 to 6 carries 2 marks per question. Answer in about thirty words.
• Questions 7 to 18 carries 3 marks per question. Answer in fifty words.
• Questions 19 to 24 carries 5 marks per question. Answer in about seventy words.
• Section B: (consists of both Objective & Descriptive type of Questions)
• Questions 25 to 33 carries 1 mark per question & are objective types of questions.
• Questions 34 to 36 carries 2 marks per question & are descriptive types of questions.
• Answers without relevant diagram / figure / circuit wherever necessary will not carry any marks.
• Numerical problems solved without writing the relevant formulae carry no marks.
• Use of calculators is prohibited.
• There is no overall choice.
• No clarification will be entertained during the examination. Doubts in the paper can be reported to the coordinator after the exam.

Section – A

Answer the questions in one word or in one sentence. Each correct answer carries 1 mark.

1. Name the following compounds.

2. What is the magnification of the images formed by plane mirrors and why?

3. What is speciation?

4. What is meant by power of a lens? What does its sign (+ve or –ve) indicate? State its S.I. unit. How is this unit related to focal length of lens?

5. List four advantages of properly managed watershed management.

6. With the help of an example, explain the process of hydrogenation. Mention the essential conditions for the reaction and state the change in physical property with the formation of the product.

Answer the questions in fifty words. Each correct answer carries 3 marks.

7. What is meant by pollination? Name and differentiate between the two modes of pollination in flowering plants.

8. What are covalent compounds? Why are they different from ionic compounds? List their three characteristic properties.

9. Suggest three contraceptive methods to control the size of human population, which is essential for the health and prosperity of a country. State the basic principle involved in each.

10. Draw the following diagram in which a ray of light is incident on a concave/convex mirror on your answer sheet. Show the path of this ray, after reflection, in each case.

11. The activities of man have adverse effects on all forms of living organisms in the biosphere. Unlimited exploitation of nature by man disturbed the delicate ecological balance between the living and the non-living components of the biosphere. The unfavourable conditions created by man himself threatened the survival not only of him, but also of the entire living organisms on the mother

earth. One of your classmates is an active member of the ‘Eco-club’ of your school which is creating environmental awareness amongst the school students, spreading the same in the society and also working hard for preventing environmental degradation of the surroundings.

(a) Why is it necessary to conserve our environment?

(b) State the importance of green and blue dustbins in the safe disposal of the household waste.

(c) List two values exhibited by your classmate who is an active member of the Eco-club of your school

12. Explain in brief the reason for each of the following:

(b) Delayed sunset

(c) Twinkling of stars

13. How many groups and periods are there in the modern periodic table? How do the atomic size and metallic character of elements vary as we move:

(a) down a group and

(b) from left to right in a period

14. What is DNA copying? State its importance.

15. From the following elements:

${ }_{4} \mathrm{Be} ;{ }_{9} \mathrm{~F} ;{ }_{19} \mathrm{~K} ;{ }_{20} \mathrm{Ca}$

(i) Select the element having one electron in the outermost shell.

(ii) Two elements of the same group.

Write the formula of and mention the nature of the compound formed by the union of ${ }_{19} \mathrm{~K}$ and element $\mathrm{X}(2,8,7)$.

16. Draw the electron-dot structure for ethyne. A mixture of ethyne and oxygen is burnt for welding.

17. In your opinion, why cannot we use a mixture of ethyne and air for this purpose?

(a) Name the following:

(i) Thread like non-reproductive structures present in Rhizopus.

(ii) ‘Blobs’ that develop at the tips of the non-reproductive threads in Rhizopus.

(b) Explain how these structures protect themselves and what is the function of the structures released from the ‘blobs’ in Rhizopus.

18. “A convex lens can form a magnified erect as well as magnified inverted image of an object placed in front of it”. Draw ray diagram to justify this statement stating the position of the object with respect to the lens in each case.

An object of height 4 cm is placed at a distance 20cm from a concave lens of focal length 10cm. Use lens formula to determine the position of the image formed.

19. (a) Draw a ray diagram to show the formation image by a concave lens when an object is placed in front of it.

(b) In the above diagram mark the object distance (u) and the image distance (v) with their proper signs(+ve or –ve as per the new Cartesian sign convention ) and state how these distances are related to the focal length (f) of the concave lens in the case.

(c) Find the nature and power of a lens which forms a real and inverted image of magnification-1 at a distance of d 40cm from the optical centre.

20. Define evolution. How does it occur? Describe how fossils provide us evidences in support of evolution.

21. At what distance from a concave lens of local length 20cm a 6 cm tall object is placed so as to obtain its   image   at   15cm   from   the   lens?   Also   calculate   the   size    of    the    image    formed.   Draw a ray diagram to justify your answer for the above situation and label it.

22. (a) State the laws of refraction of light. Explain the term absolute refractive index of medium and write an expression to relate it with the speed of light in vacuum.

(b) The absolute refractive indices of two media ‘$\mathrm{A}$ and ‘$\mathrm{B}$’ are $2.0$ and $1.5$ respectively. If the speed

of light in medium ‘$\mathrm{B}$’ is $2 \times 10^{8} \mathrm{~m} / \mathrm{s}$, calculate the speed of light in:

(i) vacuum

(ii) medium ‘ $\mathrm{A}$’

23. The image of a candle flame placed at a distance of 30cm from a spherical lens is formed on a screen placed on the other side of the lens at a distance of d 60 cm from the optical centre of the lens. Identify the type of lens and calculate its focal length. If the height of the flame is 3cm . Find the height of its image.

24. (a) Name the human male reproductive organ that produces sperms and also secretes a hormone. Write the functions of the secreted hormone.

(b) Name the parts of the human female reproductive system where

(i) fertilisation takes place

(ii) implantation of the fertilised egg occurs.

Explain how the embryo gets nourishment inside the mother’s body.

Section – B

25. A student obtained a sharp image of a candle flame placed at the distant end of the laboratory table on a screen using a concave mirror to determine its focal length. The teacher suggested him to focus a distant building, about 1 km away from the laboratory, for getting more correct value of the focal length. In order to focus the distant building on the same screen, the student should slightly move the

(a) mirror away from the screen (b) screen away from the mirror

(c) screen towards the mirror               (d) screen towards the building

26. A student has to perform the experiment “To identify the different parts of an embryo of a dicot seed”. Select from the following an appropriate group of seeds:

(a)Pea, gram, wheat                               (b) Red kidney bean, maize, gram

(c) Maize, wheat, red kidney bean (d) Red kidney bean, pea, gram

27. Select from the following the best experimental setup for tracing the path of a ray of light passing through a rectangular glass slab.

(a)P (b) Q (c) R (d) S

28. Suppose you have focused on a screen the image of candle flame placed at the farthest end of the laboratory table using a convex lens. If your teacher suggests you to focus the parallel rays of the sun, reaching your laboratory table, on the same screen, what you are expected to do is to move the

(a) lens slightly towards the screen (b) lens slightly away from the screen

(c) lens slightly towards the sun (d) lens and screen both towards the sun

29. To determine the approximate value of the focal length of a given concave mirror, you focus the image of a distant object formed by the mirror on a screen. The image obtained on the screen, as compared to the object, is always

(a) laterally inverted and diminished (b) inverted and diminished

(c) erect and diminished               (d) erect and highly diminished

30. The students of a class were asked by the teacher to study the different parts of an embryo of an angiosperm. Given below are the essential steps for the experiment:

A. Soak the seeds in plain water and keep them overnight.

B. Cut open the soaked seed and observe its different parts.

C. Take some healthy seeds in a petri-dish.

D. Drain the excess water, cover the seeds with a wet cotton cloth and leave them as it is for a day.

The correct sequence of these steps is

(a) C, A, D, B (b) C, D, A, B (c) A, C, D, B (d) A, C, B, D

31. A student adds 2mL of acetic acid to a test tube containing 2mL of distilled water. He then shakes the test tube well and leaves it to settle for some time. After about 5minutes he observes that in the test tube there is :

(a) a clear transparent colourless solution

(b) a clear transparent pink solution

(c) a precipitate settling at the bottom of the test tube

(d) a layer of water over the layer of acetic acid

32. Given below is the list of vegetables available in the market. Select from these the two vegetables having homologous structures:

(a)Potato and sweet potato (b) Radish and carrot

(c) Okra and sweet potato (d) Potato and tomato

33. A student identified the various parts of an embryo of a gram seed and listed them as given below:

(I) Testa

(II) Plumule

(IV) Cotyledon

(V) Tegman

Out of these the actual parts of the embryo are:

(a) I, II, III (b) II, III, IV (c) III, IV, V (d) II, IV, V

34. What do you observe when you drop a few drops of acetic acid to test tubes containing,

(a) phenolphthalein (b) distilled water

(c) universal indicator (d) sodium hydrogen carbonate powder

35. A student focuses the image of well-illuminated distant object on a screen using a convex lens. After that, he gradually moves the object towards the lens and each time focuses its image on the screen by adjusting the lens.

(i) In which direction, towards the screen or away from the screen, does he move the lens?

(ii) What happens to the size of the image? Does it decrease or increase?

(iii) What happens to the image on the screen when he moves the object very close to the lens?

36. Draw a labelled diagram to show that particular stage of binary fission in the amoeba in which its nucleus elongates and divide into two and a constriction appears in its cell membrane.

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