CBSE 10th Science Guess Paper 2019 SET-4

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SECTION A

1. Give an example of a flower contains both stamens and carpels. [1]

2. List two indirect ways of using solar energy. [1]

SECTION B

3. The reaction of a metal ‘X’ with 𝐹𝑒2𝑂3 is highly exothermic and is used to

join broken railway tracks. Identify metal ‘X’. Write the balanced chemical

equation of its reaction with 𝐹𝑒2𝑂3. State the special name given to this

reaction. [2]

4. Can termination of pregnancy be misused by people? Justify your answer

with reason. [2]

5. “ Stars seem higher than they actually are.” Explain why? [2]

SECTION C

6. The Ph of a salt used to make tasty and crispy pakoras is 14. Identify the salt

and write a chemical equation for its formation. List its two uses. [3]

7. An element A burns with golden flame in air. It reacts with another element

B, atomic number 17 to give a product C. An aqueous solution of product C on

electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D.

Also write down the equations for the reactions for the reactions involved. [3]

OR

Two ores A and B were taken. On heating ore A gives 𝐶𝑂2 whereas, ore B gives

𝑆𝑂2. What steps will you take to convert them into metals?

CBSE 10th Science Guess Paper 2019 SET-4

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8.

Group → Period ↓

1 2 13 14 15 16 17 18

3 X B C D E 4 Y 5 Z

Using the given part of the periodic table, answer the following questions with

reason-

(i) Name the element having smallest atomic size.

(ii) Write electronic configuration of element E

(iii) Identify the elements which have similar physical and chemical

properties as the element Y. [3]

OR

An element X (atomic number 17) reacts with an element Y (atomic number

20) to form a divalent halide.

(i) Where in the periodic table are element X and Y placed.

(ii) Classify X and Y as metal(s), non-metal(s) or metalloid(s).

(iii) What will be the nature of oxide of element Y? Identify the nature of

bonding in the compound formed.

9. How does adrenaline help an athlete to prepare for running? Explain. Also

name the gland that produces this hormone. [3]

10. Draw the diagram of cross- sectional view of human brain and label: [3]

(i) the part that helps in performing voluntary actions with precision.

(ii) the part that controls salivation and vomiting.

(iii) the largest part of forebrain.

CBSE 10th Science Guess Paper 2019 SET-4

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11. (i) Name the part in human eye having light sensitive cells. [3]

(ii) Mention the reason for twinkling of stars. Draw a diagram to illustrate it.

12. A wire of length L and resistance R is stretched so that its length is

doubled and the area of cross- section is halved. How will its: [3]

(i) resistance change?

(ii) resistivity change?

Justify your answer in each case.

13. State Joule’s law of heating and give its mathematical form. [3]

An electric iron takes a current of 5A and develops 1.5× 104 J of heat energy in

30s. Calculate the resistance of the electric iron.

OR

An electric geyser rated 1500 W, 250 V is connected t 250 V line mains.

Calculate:

(i) The electric current drawn by it.

(ii) Energy consumed by it in 50 hours.

(iii) Cost of energy consumed if each unit costs ₹6.00.

14. What is biological magnification? Will the levels of this magnification be

different at different levels of the ecosystem? [3]

15. List two main causes of the pollution of water of the river Ganga. State

how pollution and contamination of river water prove harmful for the health

of the people of neighboring areas. [3]

CBSE 10th Science Guess Paper 2019 SET-4

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SECTION D

16. (i) Write the steps involved in the extraction of pure metals in the middle

of the activity series from their carbonate ores. [5]

(ii) How is copper extracted from its sulphide ore/ Explain the various steps

supported by chemical equations. Draw labeled diagram for the electrolytic

refining of copper.

17. Explain the mechanism of the cleansing action of soaps. [5]

OR

Elements forming ionic compounds attain noble gas electronic configuration

by either gaining or losing electrons from their valence shells. Explain giving

reason why carbon cannot attain such a configuration in this manner to form

its compounds. Name the type of bonds formed in ionic compounds and in the

compounds formed by carbon. Also explain with reason why carbon

compounds are generally poor conductors of electricity.

18. Name various plant hormones. Also give their physiological effects on

plant growth and development. [5]

CBSE 10th Science Guess Paper 2019 SET-4

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19. In the following crosses write the characteristics of the progeny. [5]

Cross Progeny

(i) RR YY × RR YY

Round, yellow and round, yellow

(ii) Rr Yy × Rr Yy

Round, yellow and round, yellow

(iii) rr yy × rr yy

Wrinkled, green and wrinkled, green

(iv) RR YY × rr yy

Round, yellow and wrinkled, green

OR

How has the method of ‘artificial selection by humans helped in the evolution

of different vegetables?

20. (i) How far should one hold an object from a concave mirror of focal

length 40 cm so as to get a virtual image twice the size of the object? [5]

(ii) For a concave mirror, draw ray diagrams to show the reflected ray in

following cases:

(a) A ray incident parallel to its principal axis.

(b) A ray passing through its center of curvature before being incident on

mirror.

(c) A ray incident obliquely on pole of mirror.

OR

(i) Rohit claims to have obtained an image twice the size of object with a

concave lens. Is he correct? Give reason for your answer.

(ii) Where should an object in case of a convex lens to form an image of same

size as of the object? Show with the help of ray diagram the position and the

nature of the image.

(iii) With the help of ray diagram, illustrate the change in position, nature and

CBSE 10th Science Guess Paper 2019 SET-4

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size of the image formed if the convex lens in case of (ii) is replaced by

concave lens of same focal length.

21. What is short circuiting? List two precautions to prevent it. What is the

color of insulation of earth wire? State its functions in a domestic circuit and

explain how earthing of an electric appliance saves the user from a severe

electric shock. [5]

SECTION E

22. When a student added zinc granules to dilute HCl, a colorless and odorless

gas was evolved, which was then testes with a burning matchstick; what

would be observed? [2]

23. Acetic acid was added to a solid X kept in a test tube. A colorless, odorless

gas Y is evolved. The gas was passed through lime water, which turned milky.

Identify X and Y. write the chemical equation for the reaction. [2]

OR

Some reactions are given below:

𝐶𝑢(𝑠) + 𝑍𝑛𝑆𝑂4(𝑎𝑞) → 𝑁𝑜 𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛

2𝐴𝑙(𝑠) + 3𝑍𝑛𝑆𝑂4(𝑎𝑞) → 𝐴𝑙2(𝑆𝑂4)3 + 3𝑍𝑛(𝑠)

What do you conclude about reactivity of Cu, Zn and Al from the above

reactions.

24. Mention any two factors which influence the opening of stomata. [2]

25. A student confirms binary fission process in a unicellular organisms after

observing a slide under microscope. What he might have observed in that

slide to reach conclusion? [2]

OR

CBSE 10th Science Guess Paper 2019 SET-4

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Which of the following diagrams is correct for the process of budding in Yeast

and why?

26. The teacher asks a student to fix the given screen at an appropriate place

in the given experimental set up, so that a clear image can be obtained on the

screen. If the focal length of convex lens in 8 cm, find the mark on the scale at

which he should fix up the screen? [2]

OR

A man holding a lighted candle in front of thick glass mirror and viewing it

obliquely sees a number of images of the candle. Why?

27. Draw a path of light ray passing through a prism. Label angle of incident

and angle of deviation in the ray diagram. [2]

CBSE 10th Science Guess Paper 2019 SET-4

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