(Download) CBSE Class-10 Sample Paper And Marking Scheme 2018-19 : (Science)

(Download) CBSE Class-10 Sample Paper And Marking Scheme 2018-19:

(Science)

SECTION A

1. Name a common nutrient that is absorbed in the small intestine and reabsorbed by the kidney tubules.       1

2. The presence of a particular group of bacteria in water bodies indicates contamination. Identify the group. 1

SECTION B

3. How is Magnesium Chloride formed by the transfer of electrons? Why does the solution of Magnesium chloride
conduct electricity?   2

4. In a flowering plant, summarize the events that take place after fertilization. 2

5. A ray of light enters into benzene from air. If the refractive index of benzene is 1.50, by what percent does the speed of light reduce on entering the benzene? 2

OR

For the same angle of incidence in media A,B and C, the angles of refraction are 200, 300 and 400 respectively. In which medium will the velocity of light be maximum? Give reason in support of your answer.

SECTION C

6. What happens when aqueous solutions of Sodium sulphate and Barium chloride are mixed? Give a balanced equation for the reaction with state symbols. Name and define the type of chemical reaction involved in the above change. 3

7. Identify the compound of calcium which is used for plastering of fractured bones. With the help of chemical equation show how is it prepared and what special precautions should be taken during the preparation of this compound. 3

OR

‘Sweet tooth may lead to tooth decay’. Explain why? What is the role of tooth paste in preventing cavities?

8. The electronic configuration of an element ‘X’ is 2,8,6. To which group and period of the modern periodic table does ‘X’ belong .State it valency and justify your answer in each case. 3

9. Pertaining to endocrine system, what will you interpret if- 3
i) You observe swollen neck in people living in the hills
ii) Over secretion of Growth Hormone takes place during childhood
iii) Facial hair develops in boys aged 13.

10. A variegated leaf with green and yellow patches in used for an experiment to prove that chlorophyll is required for photosynthesis. Before the experiment the green portions (A), and the pale yellow portions (B), are observed. What will be the colour of ‘A’ just before and after the starch test? Also write the equation of photosynthesis and mark, as
well as validate from which molecule the by-product is obtained. 3

11. The image of an object formed by a mirror is real, inverted and is of magnification -1. If the image is at the distance of 30 cm from the mirror, where is the object placed? Find the position of the image if the object is now moved 20 cm towards the mirror. What is the nature of the image obtained? Justify your answer with the help of ray diagram. 3

OR

What is meant by power of a lens? You have three lenses L1, L2 and L3 of powers +10D, +5D and -10D respectively. State the nature and focal length of each lens. Explain which of the three lenses will form a virtual and magnified image of an object placed at 15 cm from the lens. Draw the ray diagram in support of your answer.

12. Two lamps, one rated 100 W at 220 V and the other 200 W at 220V are connected (i) in series and (ii) in parallel to electric main supply of 220V. Find the current drawn in each case. 3

13. The figure below shows three cylindrical copper conductors along with their face areas and lengths. Compare the
resistance and the resistivity of the three conductors. Justify your answer.

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