CBSE Class 10 Science Sample Paper 2018 Solved Set B

Section A

1 Name the process of converting vegetable oil to vegetable ghee. 

2 List two secondary sexual characters of males that are different from that of females. 

3 Write the main function of Ozone in the upper atmosphere .

4 When a concave mirror is placed facing the Sun, the Sun’s rays converge to a point 10 cm from the mirror. Now, if you place a 2 cm long candles flame 20 cm away on the principal axis of the mirror, where would you place a screen to obtain the image of the candle? What would see the size of the image? Draw a ray diagram to justify your answer. 

5 If you find coliform bacteria in a sample of water collected from a river, what would you conclude? Give reason for such kind of water pollution. 

6 Which natural resources are called the “biodiversity hot spots”? How these hot spots maintain ecological balance? 

7 What are isomers? “Isomers of the first three members of alkane series are not possible”. Give reason to justify this statement and draw structures of two isomers of butane, C₄H₁₀.

8 An organic compound ‘X’ is a liquid at room temperature. It is also a very good solvent and has the molecular formula C₂H₆O. on oxidation ‘X’ gives ‘Y’ which give, break effervescence on reacting with NaHCO₃. X reacts with Y in the presence of conc.H₂SO₄ to give another compound ‘Z’ which has a pleasant smell. Identify X, Y and Z. also write chemical equations to show the formation of Y and Z.

9 An element ‘A’ belongs to 3rd period and 17th group of the periodic table. a) Write atomic member and electronic configuration of ‘A’

b) State whether A is a metal or a non – metal. c) Write the nature of bond formed if A reacts with another element B of electronic configuration 2, 8, 1. d) Write the chemical formula of the compound formed. 

10 Consider the following elements ₄Be, ₉F, ₁₉K, ₂₀Ca

a) Select the element having one election in the outer most shell. b) Select two elements of the same group. c) Write the formula and state the nature of the Compound formed when the element K reacts with an element X of electronic configuration 2, 8, 7. 

11 Explain with the help of labelled diagrams the development that takes place in each of the body parts of a Planaria where body is cut into three pieces. None this process and give an example of an organism in which a similar process can be observed. 

12 List any four methods of contraception used by humans. How does the use of three methods have a direct effect on the heath and prosperity of a family? 

13 List two functions each of the following points of human female reproductive system a) Ovaries b) Fallopian tubes c) Uterus 

14 “Different species use different strategies to determine sex of a new born individual. It can be environmental cues or genetically determined”. Justify this statement giving reason/example. 

15 List in tabular form, two distinguishing features between the acquired traits and the inherited traits with one example of each. 

16 A student has to project a three times magnified image of a candle flame on a wall. Name the type of the lens (converging/ diverging) required for the purpose. It the candle flame is at a distance of 6 m from the wall, find the focal length of the lens. 3

17 A child while playing with his father’s spectacles burnt a hole in a piece of them tissue paper by focusing the image of the Sun on at. a) Name the defect of vision his father is suffering form. b) List two causes of the defect. c) Draw a ray diagram to show how this defect may be corrected using a suitable lens. 

18 Some residents of your colony are planning to cut trees to create a place for parking vehicles. You are upset by knowing all this and wanted to do something to create awareness about the importance of trees. (a) List any three reasons that you will use to convince residents of your colony not to cut the existing trees. (b) List any three values that would be inculcated amongst them with such approach. 

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