CLASS - X
SCIENCE (THEORY)

SAMPLE PAPER I

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 are to be attempted separately.
5. Questions 1 to 6 in section A and 17 to 19 in section B are short question.These carry one mark each.
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. A ray of light LM is incident on a mirror as shown in the figure. The angle of incidence for this ray is the angle between it and the line joining two other points in the figure. Name these two points.

2. Metals generally occur in solid state. Name and write symbol of a metal that exists in liquid state at room temperature.

3. During summer season, a milkman usually adds a very small amount of baking soda to fresh milk. Give one reason.

4. The following table gives the values of refractive indices of a few media.
S.No. 1 2 3 4 5 Medium Water Crown Glass Rock salt Ruby Diamond Refractive 1.33 1.52 1.54 1.71 2.42 Index Use this table to give an example of :
(i) a medium pair so that light speeds up when it goes from one of these media to another.
(ii) a medium pair so that light slows down when it goes from one of these media to another.

5. Why potato chips manufacturers fill the packet of chips with nitrogen gas?

6. Alloys are used in electrical heating devices rather than pure metals. Give one reason.

7. Tooth enamel is one of the hardest substances in our body. How does it undergo damage due to eating chocolates and sweets? What should we do to prevent it?

8. A student has been collecting silver coins and copper coins. One day she observed a black coating on silver coins and a green coating on copper coins. Which chemical phenomenon is responsible for these coatings? Write the chemical name of black and green coatings.

9. Two students perform the experiments on series and parallel combinations of two given resistors R1 and R2 and plot the following V-I graphs. Which of the graphs is (are) correctly labelled in terms of the words ‘series’ and parallel’  Justify your answer.

10. Draw the pattern of magnetic field lines of a current carrying solenoid. What does the pattern of field lines inside the solenoid indicate? Write one application of magnetic field of current carrying solenoid.

11. A student finds the writing on the blackboard as blurred and unclear when sitting on the last desk in the classroom. He however, sees it clearly when sitting on the front desk at an approximate distance of 2m from the blackboard. Draw ray diagrams to illustrate the formation of image of the blackboard writing by his eye-lens when he is seated at the (i) last desk (ii) front desk. Name the kind of lens that would help him to see clearly even when he is seated at the last desk. Draw a ray diagram to illustrate how this lens helps him to see clearly.

12. State which of the following chemical reactions will take place or not, giving suitable reason for each.
Zn (s) + Cu SO4 (aq) —-> Zn SO4 (aq) + Cu (s)
Fe (s) + Zn SO4 (aq) —-> Fe SO4 (aq) + Zn (s)
Zn (s) + Fe SO4 (aq) —-> Zn SO4 (aq) + Fe (s)

13. (a) Two lenses have power of (i) + 2D (ii) - 4D. What is the nature and focal length of each lens.?
(b) An object is kept at a distance of 100cm from each of above lenses.
Calculate the (i) image distance (ii) magnification in each of the two cases.

14. The following table shows the position of six elements A, B, C, D, E and F in the periodic table.
Groups 1 2 3 to 12 13 14 15 16 17 18
Periods
2. A B C
3. D E F
Using the above table answer the following questions :
(a) Which element will form only covalent compunds?
(b) Which element is a metal with valency 2?
(c) Which element is a non-metal with valency of 3?
(d) Out of D and E, which one has a bigger atomic radius and why?
(e) Write a common name for the family of elements C and F.

15. An organic compound ‘A’ is widely used as a preservative in pickles and has a molecular formula C2H2O2. This compound reacts with ethanol to form a sweet smelling compound ‘B.
(i) Identify the compound ‘A’
(ii) Write the chemical equation for its reaction with ethanol to form compound ‘B’.
(iii) How can we get compound ‘A’ back from ‘B’?
(iv) Name the process and write corresponding chemical equation.
(v) Which gas is produced when compound ‘A’ reacts with washing soda?
write the chemical equation.

OR

(a) Why does carbon form largest number of compounds?
(b) Why are some of these called saturated and other unsaturated compounds?
(c) Which of these two is more reactive?
(d) Write the names of the compounds.

16. In a household electric circuit different appliances are connected in parallel to one another. Give two reasons. An electrician puts a fuse of rating 5A in that part of domestic electrical circuit in which an electrical heater of rating 1.5kW, 220V is operating. What is likely to happen in this case and why? What change, if any, needs to be made?

OR

You are given following current-time graphs from two different sources:
(i) Name the type of current in two cases.
(ii) Identify any one source for each type of these currents.
(iii) What is the frequency of current in case II in India?
(iv) Use above graphs to write two difference between the current in two cases.

SECTION B
17. After a vigorous exercise, you may experience cramps in your leg muscles. Why does this happen? 1

18. Which organ secretes a hormone when the blood sugar rises. Name a digestive enzyme released by this organ. 1

19. Name two gases, other than carbon-di-oxide, that are given out during burning of fossil fuel and contribute towards acid rain formation. 1

20. Out of two solar cookers, one was covered by a plane glass slab and the other was left open. Which of the two solar cookers will be more efficient and why? 2

21. In the flow chart given below, fill in the blank spaces with the kind of energy available. 2

22. By comparing the similarity of nucleotide sequences in DNA of different kinds of organisms, evolutionary relationships can be established
(i) Arrange the following according to their evolutionary closeness. (You may use your knowledge of classification also).
(ii) Whose DNA among the following do you think is most similar to that of humans? 2
cockroach,  mango tree,  gorilla,  fish

23. Study carefully the food chains given below:-
Food chain I : grass - grasshopper - frog
Food chain II : wheat - rat - snake - hawk

To which of the two consumers, snake or hawk will more energy (percent) be available and why? 2

24. What do the following transport?
(i) xylem
(ii) phloem
(iii) pulmonary vein
(iv) Vena Cava

25. Give one term caption for
the two pictures given here.
Define the term and give
its signifance in evolution 3

26. Why are environmentalists insisting upon ‘sustainable natural resource management’?
Give any three reasons?

27. Study the given data and answer the questions following the data. Parental plants F1 (first generation off spring) F2 (offspring of self pollination of F1 cross fertilised & seeds collected Male parent 330 seeds sown Out of 44 seeds always bore and observed 33 seeds red flowers. gave plants with Female parent All 330 gave red flowers and always had red flowers 11 seeds gave plants with white flowers. white flowers :
(i) What is the term for this type of cross?
(ii) What does the data of the column marked F1 indicate?
(iii) Express the genotype of the (a) parents (b) F1 Progeny and (c) F2 Progeny 5

OR

Study the picture given below and comment on the encircled organisms with respect to :
(i) the category according to the food they eat.
(ii) trophic level to which they belong.
(iii) percentage of energy available at their trophic level.
(iv) two abiotic components of the ecosystem inhabited by them.
(v) energy used for food production by the producers.