Class -X SCIENCE (THEORY) SAMPLE PAPER III
Time : 2½ Hours Max. Marks : 60

General Instructions

1. The question paper comprises of two sections A and B. You are to attempt both the sections.
2. All questions are compulsory.
3. There is no overall choice However, internal choice has been provided in all the three questions of five marks category. Only one option in such questions is to be attempted.
4. All questions of section A and all questions of section B are to be attempted separately.
5. Questions 1 to 6 in section A and 17 to 19 in section B are to be attempted separately.
6. Questions 7 to 10 in section A and 20 to 24 in section B are short answer type questions and carry two marks each.
7. Questions 11 to 14 in section A and 25 to 26 in section B are also short answer type questions and carry three marks each.
8. Questions 15 and 16 in section A and question 27 in section B are long answer type questions and carry five marks each.

SECTION A

1. Dry Hydrogen Chloride gas does not turn blue litmus red whereas Hydrochloric acid does. Give one reason.

2. Identify the substance oxidised and reduced in the chemical reaction :
Mn O2 + 4 HCl ——> Mn Cl2 + Cl2 + 2H2O

3. You are give three resistors of 10 ?, 10 ? and 20 ?, a battery of emf 2.5V, a key, an ammeter and a voltmeter. Draw a circuit diagram showing the correct connections of all given components such that the voltmeter gives a reading of 2.0V.

4. Sketch magnetic field lines arround a current carrying straight conductor.

5. The electrical resistivity of few materials is given below in ohm-meter. Which of these materials can be used for making element of a heating device?
A 6.84 x 10-8
B 1.60 x 10-8
C 1.00 x 10-4
D 2.50 x 1012
E 4.40 x 10-5
F 2.30 x 1017

6. Refractive index of media A, B, C and D are 26
A 1.33
B 1.52
C 1.44
D 1.65
In which of the four media is the speed of light (i) maximum (ii) minimum.?

7. A metal is treated with dilute sulphuric acid. The gas evolved is collected by the method shown in the figure. Answer the following.
(i) Name the gas.
(ii) Name the method of collection of the gas.
(iii) Is the gas soluble or insoluble in water?
(iv) Is the gas lighter or heavier than air?

8. A household uses the following electric appliances :
(i) Refrigerator of rating 400W for ten hours each day.
(ii) Two electric fans of rating 80W each for twelve hours each day.
(iii) Six electric tubes of rating 18W each for 6 hours each day.
Calculate the electricity bill of the household for the month of June if the cost per unit of electric energy is Rs. 3.00.

9. What is the meaning of the term ‘frequency’ of an alternating current? What is its value in India? Why is an alternating current considered to be advantageous over direct current for long range transmission of electric energy?

10. A person is able to see objects clearly only when these are lying at distances between 50cm and 300cm from his eye.
a) What kind of defects of vision he is suffering from?
b) What kind of lenses will be required to increase his range of vision from 25cm to infinity? Explain briefly.

11. A student dropped few pieces of marble in dilute Hydrochloric acid contained in a test tube. The envolved gas was passed through lime water. What change would be observed in lime water? Write balanced chemical equations for both the changes observed.

12. Atomic number is considered to be a more appropriate parameter than atomic mass for classification of elements in a periodic table. Why? How does atomic size of elements vary on moving from
(i) left to right in a period.
(ii) from top to bottom in a group.
Give reasons for your answers.

13. Why does a current carrying conductor kept in a magnetic field experience force? On 27 what factors does the direction of this force depend? Name and state the rule used for determination of direction of this force.

14. Answer the following:
(a) Why is Plaster of Paris written as CaSo4 • ½ H2O? How is it possible to have half a water molecule attached to CaSO4?
(b) Why is Sodium Hydrogen Carbonate an essential ingradiant in antacids.?
(c) When electricity is passed through an acquous solution of sodium chloride, three products are obtained. Why is the process called chlor-alkali?

15. Four metals A, B, C and D are, in turn, added to the following solutions one by one. The observations made are tabulatd below: Metal Iron (II) Sulphate Copper (II) Sulphate Zinc Sulphate Silver Nitrate
A No reaction Displacement — —
B Displacement — No reaction —
C No reaction No reaction No reaction Displacement
D No reaction No reaction No reaction No reaction
Answer the following questions based on above information.

(i) Which is the most active metal and why?
(ii) What would be observed if B is added to a solution of copper (II) sulphate and why?
(iii) Arrange the metals A, B, C and D in order of increasing reactivity.
(iv) Container of which metal can be used to store both zinc sulphate solution and silver nitrate solution.
(v) Which of the above solutions can be easily stored in a container made up of any of these metals?

OR

You are given the following materials:
(i) Iron nails
(ii) Copper sulphate solution
(iii) Barium chloride solution
(iv) Copper powder
(v) Ferrous sulphate crystals
(vi) Quick Lime

Identify the type of chemical reaction taking place when.

(a) Barium chloride solution is mixed with copper sulphate solution and a white precipitate is observed.
(b) On heating copper powder in air in a China dish, the surface of copper powder turns black.
(c) On heating green coloured ferrous sulphate crystals, reddish brown solid is left 28 and smell of a gas having odour of burning sulphur is experienced.
(d) Iron nails when left dipped in blue copper sulphate solution become brownish in colour and the blue colour of copper sulphate fades away.
(e) Quick lime reacts vigorously with water releasing a large amount of heat.

16. Draw ray diagrams to show the formation of a three times magnified (i) real image (ii) virtual image of an object kept in front of a converging lens. Mark the positions of object, F, 2F, O and position of image clearly in the diagram. An object of size 5 cm is kept at a distance of 25cm from the optical centre of a converging lens of focal length 10cm. Calculate the distance of the image from the lens and size of the image.

OR

Give reasons for the following:
(i) The sky appears to be blue during day time to a person on earth.
(ii) The sky near the horizon appears to have a reddish heu at the time of sunset and sunrise.
(iii) The sky appears dark instead of blue to an astronaut.
(iv) The stars appears to twinkle.
(v) The planets do not twinkle.

SECTION B

17. Justify in one sentence that hydropower (hydel electricity) is a renewable source of energy. 1

18. ‘Malarial parasite’ divides into many daughter individuals simultaneously through multiple fission. State an advantage the parasite gets because of this type of reproduction. 1

19. The human hand, cat paw and the horse foot, when studied in detail show the same structure of bones and point towards a common origin.
(i) What do you conclude from this?
(ii) What is the term given to such structures? 1

20. In the test tubes A and B shown below, yeast was kept in sugar solution. Which products of
respiration would you expect in tubes A and B?

21. Write one feature which is common to each of the following pairs of terms / organs.
(i) glycogen and starch ; (ii) chlorophyll and haemoglobin
(iii) gills and lungs (iv) arteries and veins 2

22. The given experimental set up tests the response of different parts of plant towards gravity. Use scientific terms for the conclusions.

23. Select the biodegradable items from the list given below. Polythene bags, old clothes, wilted flowers, pencil shavings, glass bangles, bronze statue vegetable peels.

24. Given above is a picture of an ecosystem. Identify any two abiotic components and any two biotic components of this ecosystem.

25. Quote three instances where human intervention saved the forests from destruction.

26. Label parts 1 to 6 in the given figure of the brain

27. Explain that it is a matter of chance whether a couple will give birth to a boy or a girl.

OR

Which hormone is released into blood when its sugar level rises? Name the organ which produces the hormone and its effect on blood sugar level. Also name one digestive enzyme that this organ secretes and the function of this enzyme.