X- SCIENCE

CLASS X

SCIENCE

TIME: 3 HRS M.M. 80

General Instructions-
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i. The question paper comprises of five sections – A, B, C, D and E. You are to attempt all the sections.

ii. All questions are compulsory.

iii. Internal choice is given in sections B, C, D, and E.

iv. Question no. 1 and 2 in section A are 1 mark each. They have to be answered in one word or one sentence.

v. Question no. 3 to 5 of section B are of 2 marks each. Theses have to be answered in about 30 words each.

vi. Question no. 6 to 15 of section C are of 3 marks each. Theses have to be answered in about 50 words each.

vii. Question no. 16 to 21 of section D are of 5 marks each. Theses have to be answered in about 70 words each.

viii. Question no. 21 to 27 of section E are based on practical skills. Each question is of 2 marks. These are to be answered in brief.
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SECTION A

1. What is the role of rings of cartilage in the throat? (1)

2. Which liquid is used in ocean Thermal Energy? (1)


SECION B

 3. Write the name and equation for the reaction used in repairing railway tracks. (2)

4. What are the advantages of vegetative propagation? (Any two) (2)

 5. Light enters from air to glass having refractive index 1.50. What is the speed of light in glass?
(c = 3 x 108 m/s.) (2)

OR

Refractive indices of Kerosene, turpentine and water are 1.44, 1.47 and 1.33 respectively. In which
medium is the speed of light faster? Where will the light bend when it enters from Kerosene to water?

SECTION -C

6. Compound A when dissolved in water gives compound B which is used in whitewashing. Compound B
reacts with CO2 to form compound C. Identify A, B, C and write the 2 equations. (3)

7. (a) What is Chlor-alkali process ?

 (b) What happens on the action of Chlorine on slaked lime?
 Write both equations also (3)

OR

Salt A, one of the component of baking powder gets converted to B on heating. B is used for removing
hardness of water and gas C is evolved which turns lime water milky. Identify A, B, C. Write the equation also.

8. The atomic numbers of 5 elements are A=4, B=9, C=14, D=19, E=20. (3)

(a) Select the element that has one electron in the outermost shell. Write the electronic configuration.

(b) Which 2 elements belong to the same group? Give reasons.

(c) Which 2 elements belong to the same period? Which one have a bigger atomic radius?
9. Name the hormones secreted by the following endocrine glands:
(a) Pituitary (b) Pancreas (c) Thyroid (d) Testes (e) Ovary (f) Adrenal (3)

10. Give reasons:

(a) Veins have thin walls as compared to arteries.

(b) Rate of breathing is faster in aquatic organisms than terrestrial organism.

(c) Intestine of herbivores is longer than carnivores.

11. A 2.0 cm tall object is placed perpendicular to the principal axis of a concave mirror of focal length 10 cm. The distance of the object from the mirror is 15 cm. Find the nature, position and size of the image.
Represent this with a diagram. (3)

OR

(a) What is meant by power of lens?

(b) Write it's unit.

(c) If power is +2.0 D. Write the type of lens and find it's focal length.

12. A geyser is rated 1500 W and 250 V. It is connected to 250V mains. Calculate the : (3)

 (i) Current drawn

 (ii) Energy consumed in 50 hrs.

 (iii) Cost of energy at Rs. 2.20 per unit.

13. (a) Resistivity of four materials is as follows : (3)

A=1.62X10-8 Ωm, B=1.84X10-6 Ωm
C=100X10-6 Ωm, D=1012 Ωm.
Which of them is the best conductor and the best insulator?

 (b) Why are alloys used in heating instruments?

 (c) Why is voltmeter connected in parallel?

14. (a) Write the energy conversion in hydro-power plant? (3)

 (b) What are the limitations in the construction of dams?

15.(a) What is biological magnification? (2+1)

 (b) Why is food chain unidirectional?

OR

(i) How would you dispose the following wastes:

 (a) Vegetable peel

 (b) Metallic wastes

 (c) Plastic

(ii) Write the four stakeholders of forests.

SECTION-  D

16. (i) write the colours and names of compounds formed on corrosion of silver, copper, iron. (3+2)

 (ii) Why is H2 gas not released when metal reacts with HNO3?

17. A compound X is formed by the reaction of a carboxylic acid C2H4O2 and an alcohol in the (4+1)
presence of a few drops of H2SO4. Give the names and structures of (a) the carboxylic acid

(b) the alcohol and (i) the compound C? Also write the reaction.

 (ii) Why do some hydrocarbons give a yellow flame and some blue?

OR

(i) What is the difference between soap and detergent?

(ii) Explain the cleaning action of soap.

(iii) Write the equation for saponification.

18. (a) Draw a well labelled diagram of a bisexual flower L.S. (5)

 (b) Write the various contraceptive methods used to control human population.

19. (a) What is the difference between homologous and analogous organs? (5)

 (b) What is DNA copying and what is its significance?

 (c) How is the chromosome number restored after sexual reproduction?

OR

 (a) How do Mendel’s experiments show that two separate trails are inherited independently?

 (b) What are the tools used for tracing evolutionary relationship?

20. (a) what is Myopia? Why is it caused? How can it be concreted? Draw a ray diagram for (5)
Myopia and after the correction of the defect.

 (b) Why is the colour of the sky blue?

 (c) Why is the danger signal red?

21. (a) What do the three different colours of wire used is domestic circuits signify? (5)

 (b) What is fuse and what is its function?

 (c) What is the role of a commutator in an electric motor?

 (d) What is over loading and short circuiting?

OR

 (i) With the help of an activity, explain the method of inducing electric current in a coil using a moving
magnet. State the rule used to find the direction of electric current thus generated in the coil

 (ii) Two circular coils P and Q are kept close to each other of which coil P carries current what will you 
observe in Q?

 (a) If current in coil P is changed

 (b) If both the coils are moved in the same direction with same speed.

Section – E

22. What is the effect of acetic acid on? (2)

 (i) Litmus paper

 (ii) Sodium hydrogen carbonate.

OR

 When a student added zinc granules to dil. HCl a gas was released. What is this gas? How will you test it?

23. In an experiment to show that CO2 is produced during respiration (2)

 (i) Why is KOH solution used?

 (ii) Why is the conical flask fitted with a cork?

24. In a voltmeter there are 20 divisions between O mark and 0.5v mark. Calculate the least count of the (2)
voltmeter

OR

 In the following circuit diagram, which two components are connected in series and which in parallel?

25. In an experiment to trace the path of a ray of light through a rectangular glass slab:- (2)

 (i) How are the incident and emergent ray related?

 (ii) How are i and e related?

26. Draw a well labelled diagram of the embryo of a dicot seed and write the role of cotyledons. (2)

27. Draw a diagram to show refraction of light through a triangular glass prism and show i e and (2)
D.

OR

 Draw a diagram to show image formed by a convex lens when the object is placed beyond 2F. 

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