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Thursday, 31 December 2015

Model sample paper science SA 2 10

                                       
                              SECTION A
1. The atomic numbers of three elements A, B and C are 12, 18 and 20 respectively. State, giving reason, which two elements will show similar properties. (1)

2. No two individuals are absolutely alike in a population. Why? (1)
3. Write one negative effect of affluent lifestyle of few persons on the
environment. (1)

4. Draw labelled diagrams to illustrate budding in Hydra. (2)

5. "A concave mirror of focal length 15 cm can form a magnified, erect as well as  inverted image of an object placed in front of it." Justify this statement stating the position of the object with respect to the pole of the mirror in both the cases for obtaining the images. (2)

6. State with reason any two possible consequences of elimination of decomposers  from the Earth. (2)

7. What is water harvesting? How can this technique help in the conservation of water? (2)


8. Study the following table in which positions of six elements A, B, C, D, E and F are shown as they are in the modern periodic table: (3)









On the basis of the above table, answer the following questions:
(i) Name the element which forms only covalent compounds.
(ii) Name the element which is a metal with valency three.
(iii) Name the element which is a non-metal with valency three.
(iv) Out of D and E, which is bigger in size and why?
(v) Write the common name for the family to which the elements C and F belong.

9. The elements Be, Mg and Ca each having two electrons in their outermost shells are in periods 2, 3, and 4 respectively of the modern periodic table. Answer the
following questions, giving justification in each case: (3)
(i) Write the group to which these elements belong.
(ii) Name the least reactive element.
(iii) Name the element having largest atomic radius.


10. A carboxylic acid (molecular formula C2H402) reacts with an alcohol in the presence of an acid catalyst to form a compound 'X'. The alcohol on oxidation with alkaline KMnO4 followed by acidification gives the same carboxylic acid C2H402. 
Write the name and structure of
(i) carboxylic acid, (ii) alcohol and (iii) the compound 'X'. (3)

11. Define the term ‘structural’ isomerism'. Explain why propane cannot exhibit this property. Draw the structures of possible isomers of butane, C4H10 . (3)

12. A student wants to project the image of a candle flame on a screen 90 cm in front of a mirror by keeping the flame at a distance of 15 cm from its pole. (3)
(a) Suggest the type of mirror he should use.
(b) Determine the linear magnification in this case.
(c) Find the distance between the object and its image.
(d) Draw ray diagram to show the image formation in this case.
13. Draw a ray diagram to show the path of the refracted ray in each of the following cases: (3)
A ray of light incident on a concave lens is
(i) passing through its optical centre.
(ii) parallel to its principal axis.
(iii) directed towards its principal focus.
14. A narrow beam PQ of white light is passing through a glass prism ABC as shown in the diagram. (3)
Model sample paper  science  SA 2  10


Model sample paper  science  SA 2  10

16. Write one difference between asexual and sexual mode of reproduction. Which species is likely to have better chances of survival - the one reproducing asexually or
the one reproducing sexually? Justify your answer. (3)

17. What is the effect of DNA copying, which is not perfectly accurate, on the reproduction process? How does the amount of DNA remain constant though each new generation is a combination of DNA copies of two individuals? (3)

18. List three main factors responsible for the speciation and briefly describe each one of them. (3)

19. "A trait may be inherited, but may not be expressed." Justify this statement with the help of a suitable example. (3)

20. List two reasons for carbon forming a large number of compounds. Name the type of bonding found in most of its compounds. Why does carbon form compounds mainly by this kind of bonding?
Give reason why the carbon compounds- (5)
(i) generally have low melting and boiling points.
(ii) do not conduct electricity in molten state.

21. (a) List the parts of the human eye that control the amount of light entering into it. Explain how they perform this function.

(b) Write the function of retina in human eye.

(c) Do you know that the corneal-impairment can be cured by replacing the defective cornea with the cornea of the donated eye? How and why should we organise groups to motivate the community members to donate their eyes after death? (3)

22. (a) Explain the following terms related to spherical lenses:
(i) optical centre
(ii) centres of curvature
(iii) principal axis
(iv) aperture
(v) principal focus
(vi)focal length


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