CBSE Board Question Paper 2009

Class – X (Foreign)

SCIENCE (Theory)

Time allowed: (2+1/2) Hours                                        Maximum marks : 60

General Instructions:

(i) The question paper comprises of two sections, A and B. You are to attempt both the sections.
(ii) All questions are compulsory.
(iii) 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.
(iv) All questions of Section A and all questions of Section B are to he attempted separately.
(v) Questions number 1 to 6 in Section A and 17 to 19 in Section B are short answer type questions. These questions carry one mark each.
(vi) Questions number 7 to 10 in Section A and 20 to 24 in Section B are short answer type questions and carry two marks each.
(vii) Questions number 11 to 14 in Section A and 25 and 26 in Section B are also short answer type questions and carry three marks each.
(viii) Questions number 15 and 16 in Section A and question number 27 in Section B are long answer type questions and carry five marks each.

SECTION – A

1. What change in colour is observed when white silver chloride is left exposed to sunlight ? What type of chemical reaction is this ?                       1

2. Which gas is generally liberated when a dilute solution of hydrochloric acid reacts with an active metal ?              1

3. Arrange the following metals.in a decreasing order of activity                               1

                                Na, K, Cu, Ag

4. What kind of mirrors are used in big shopping stores to watch activities of customers ?                    1

5. Draw a ray diagram to determine the position of image formed of an object placed between the pole and the focus of a concave mirror.                                  1

6. What will be the observed colour of sky on a planet where there is no atmosphere ? Why ?                        1

7. What is meant by ‘water of crystallization’ of a substance ? Describe an activity to show that blue copper sulphate crystals contain water of crystallization.                       2

8. What is a redox reaction ? When a magnesium ribbon burns in air with a dazzling flame and forms a white ash, is magnesium oxidised or reduced ? Why ?                            2

9. The refractive index of water is 1.33 and the speed of light in air is 3 x 108 ms^-1. Calculate the speed of light in water.                           2

10. (a) What is the shape of the graph obtained by plotting potential difference applied across a conductor against the current flowing through it ?                           

      (b) What does the slope of this V - I graph at any point represent ?                               2

11. Give reasons for the following observations :                                                                 3

      (i) Ionic compounds in general have high melting and boiling points.

      (ii) Highly reactive metals cannot be obtained from their oxides by heating them with carbon.

      (iii) Copper vessels get a green coat when left exposed to air in rainy season.

12. (a) What are ‘groups’ and ‘periods’ in the ‘periodic table’?

      (b) Two elements M and N belong to groups I and II respectively and are in the same period of the periodic table. How do the following properties of M and N vary ?                                                              3

      (i) Sizes of their atoms

      (ii) Their metallic characters

      (iii) Their valencies in forming oxides

      (iv) Molecular formulae of their chlorides

13. (a) What is Presbyopia ? State the cause of Presbyopia. How is Presbyopia of a person corrected ?

      (b) What is meant- by power of accommodation of the eye of a person ?                        3

14. (a) Draw a schematic labelled diagram of a domestic wiring circuit which includes
      (i)    a main fuse
      (ii)    a power meter
      (iii)    one light point
      (iv)    a power output socket

      (b) In this circuit, on which wire of the circuit is the mains on/off switch connected ?                          3

15. (a) The structural formula of an ester is

       Write the structural formulae of the corresponding alcohol and the acid.

     (b) (i) Mention the experimental conditions involved in obtaining ethene from ethanol.
          (ii) Write the chemical equation for the above reaction.
     (c) Explain the cleansing action of soap.                                                                                                    5

                                                    OR

(a) Write the names of the functional groups in :

(b) Describe a chemical test to distinguish between ethanol and ethanoic acid.

(c) Write a chemical equation to represent what happens when hydrogen gas is passed through an unsaturated hydrocarbon in the presence of nickel acting as a catalyst.                                                                                 5

16. (a) Two resistors R1 and R2 may form (i) a series combination or (ii) a parallel combination, and the combination may be connected to a battery of six volts. In which combination will the potential difference across R1 and across R2 be the same and in which combination will the current through R1 and through R2 be the same ?

     (b) For the circuit, shown in this diagram,

calculate
       (i)    the resultant resistance
       (ii)    the total current
       (iii)    the voltage across 7 0 resistor                                                                      5
                                                    OR
(a)    List the factors on which the resistance of a conductor depends.
(b)    A 4 kW heater is connected to a 220 V source of power. Calculate
       (i)    the electric current passing through the heater.
       (ii)    the resistance of the heater.
       (iii)    the electric energy consumed in a 2 hours use of the heater.                                         5

Section – B

17. Which disease is caused in human beings due to a depletion of ozone layer in the atmosphere ?          1

18. Which endocrine gland secretes the growth hormone ?                                                                          1

19. Which one of the following actions on touch is an example of chemical control ?                                    1

                 Movement on the touch-sensitive plant

                 Movement in human leg

20. Draw a labelled schematic diagram of a biogas plant. What use is made of the slurry left behind in biogas plants ?      2

21. List any four limitations of the energy obtained from oceans.                                         2

22. How do advantages of exploiting natural resources with short-term aims differ from the advantages of managing our resources with a long-term perspective ?                                 2

23. What is meant by wild life ? How is wild life important for us ?                            2

24. Draw a diagram of the longitudinal section of a flower and label on it (i) stigma and (ii) ovary.                2

25. What is a reflex action ? Describe the steps involved in a reflex action.                                                    3

26. What are fossils' ? Describe the importance of fossils in deciding evolutionary relationships between organisms.        3

27. (a) Draw a diagram of the human respiratory system and label on it Alveolar Sac, Bronchioles, Larynx and Trachea.

      (b) How are the lungs designed in human beings to maximize the area of exchange of gases ?               5

                                                    OR

(a) Draw a schematic representation of transport and exchange of oxygen and carbon dioxide during transportation of blood in human beings and label on it :

Lung capillaries, Pulmonary artery to lungs, Aorta to body, Pulmonary veins from lungs.

(b) What is the advantage of separate channels in mammals and birds for oxygenated and deoxygenated blood ?        5