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# CBSE Class 10 - Science

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CBSE X - Set -3
SCIENCE PAPER 2010

Time allowed: 150 minutes; Maximum Marks: 60

 General Instructions: 1) All questions are compulsory. 2) The question paper consists of 28 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. Name the part of our eyes that helps us to focus near and distant objects in quick succession.

### Question 2

2. The outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror. What will be the focal length of this mirror? Which type of spherical mirror will it provide?

### Question 3

3.

What is nature of the image formed by a concave mirror if the magnification produced by the mirror is + 4?

### Question 4

4.

A charged particle enters at right angles into a uniform magnetic field as shown. What should be the nature of charge on the particle if it begins to move in a direction pointing vertically out of the page due to its interaction with the magnetic field?

### Question 5

5. On what basis is a chemical equation balanced?

### Question 6

6. State two characteristic features of carbon which when put together give rise to a large number of carbon compounds.

### Question 20

20. Name the hormone that helps in regulating level of sugar in our blood. Name the gland that secretes it.

### Question 21

21. A person lives near a forest. Make a list of four items which he can get from the forest to meet his daily needs.

### Question 22

22. Name the green dot like structures in some cells observed by a student when a leaf peel was viewed under a microscope. What is this green colour due to?

SECTION B

### Question 7

7. Write any two observations in an activity which may suggest that a chemical reaction has taken place. Give an example in support of your answer.

### Question 8

8. What are fossil fuels? Write two disadvantages of burning fossil fuels.

### Question 9

9.

Two coils A and B of insulated wires are kept close to each other. Coil A is connected to a galvanometer while coil B is connected to a battery through a key. What would happen if

(i) a current is passed through coil B by plugging the key, and

(ii) the current is stopped by removing the plug from the key?

### Question 10

10. What is a solenoid? Draw the pattern of magnetic field lines of a solenoid through which a steady current flows. What does the pattern of field lines inside the solenoid indicate?

### Question 11

11. What is Hypermetropia (far sightedness)? Draw a ray diagram to show how this defect can be corrected using a lens.

### Question 12

12. Mention any four limitations in harnessing wind energy on a large scale.

### Question 18

18. Write the names and symbols of two most reactive metals belonging to group 1 of the periodic table. Explain by drawing electronic structure how either one of the two metals reacts with a halogen. With which name is the bond formed between these elements known and what is the class of the compound so formed known? State any four physical properties of such compounds.

### Question 19

19. What is meant by refining of metals? Name the most widely used method of refining impure metals produced by various reduction processes. Describe with the help of a labelled diagram how this method may be used for refining of copper.

### Question 23

23. What is phototropism? Describe an activity to demonstrate phototropism.

### Question 24

24. List any two differences between pollination and fertilisation.

### Question 25

25. Give one example for each of characters that are inherited and the ones that are acquired in humans. Mention the difference between the inherited and the acquired characters.

SECTION C

### Question 13

13. At what distance should an object be placed from a lens of focal length 25 cm to obtain its image on a screen placed on the other side at a distance of 50 cm from the lens? What will be the magnification produced in this case?

### Question 14

14. Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electronic shells but different number of electrons in their outermost shell. It was found that elements A and G combine to form an ionic compound. This compound is added in a small amount to almost all vegetable dishes during cooking. Oxides of elements A and B are basic in nature while those of E and F are acidic. The oxide of D is almost neutral. Based on the above information answer the following questions:

(i) To which group or period of the periodic table do the listed elements belong?

(ii) What would be the nature of compound formed by a combination of elements B and F?

(iii) Which two of these elements could definitely be metals?

(iv) Which one of the eight elements is most likely to be found in gaseous state at room temperature?

(v) If the number of electrons in the outermost shell of elements C and G be 3 and 7 respectively, write the formula of the compound formed by the combination of C and G.

### Question 15

15. No chemical reaction takes place when granules of a solid, A, are mixed with the powder of another solid, B. However when the mixture is heated, a reaction takes place between its components. One of the products, C, is a metal and settles down in the molten state while the other product, D, floats over it. It was observed that the reaction is highly exothermic.

(i) Based on the given information make an assumption about A and B and write a chemical equation for the chemical reaction indicating the conditions of reaction, physical state of reactants and products and thermal status of reaction.

(ii) Mention any two types of reactions under which above chemical reaction can be classified.

### Question 16

16. Name the functional group of organic compounds that can be hydrogenated. With the help of suitable example explain the process of hydrogenation mentioning the conditions of the reaction and any one change in physical property with the formation of the product. Name any one natural source of organic compounds that are hydrogenated.

### Question 26

26. How is ozone formed in the higher level of atmosphere? “Damage to the ozone layer is a cause of concern”. Justify this statement.

### Question 27

27. Write the full form of DNA. Name the part of the cell where it is located? Explain its role in the process of reproduction of the cell.

SECTION D

### Question 17

17. Derive the expression for the heat produced due to a current ‘I’ flowing for a time interval ‘t’ through a resistor ‘R’ having a potential difference ‘V’ across its ends. With which name is the relation known? How much heat will an instrument of 12W produce in one minute if it is connected to a battery of 12V?

OR

Explain with the help of a labelled circuit diagram how you will find the resistance of a combination of three resistors, or resistance R1, R2 and R3, joined in parallel. Also mention how you will connect the ammeter and the voltmeter in the circuit when measuring the current in the circuit and the potential difference across one of the three resistors of the combination.

### Question 28

28. Explain the process of digestion of food in mouth, stomach and small intestine in human body.

OR

(a) List the three events that occur during the process of photosynthesis. Explain the role of stomata in this process.

(b) Describe an experiment to show that “sunlight is essential for photosynthesis”.

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