#### 7 Std - Term 3-Full Study Material

7th Standard

Reg.No. :
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Science

Time : 02:15:00 Hrs
Total Marks : 60

10 x 1 = 10
1. Forest is an area with high density of __________

(a)

trees

(b)

grass

2. _______ is an example of a natural ecosystem.

(a)

(b)

Desert

3. Water exists in abundance on the planet _______

(a)

Earth

(b)

Mars

4. ______ is the gaseous form of water.

(a)

Rain

(b)

Water vapour

5. How much surface of the earth is covered with water?

(a)

80%

(b)

70%

(c)

60%

(d)

65%

6. Substances that catch fire easily are

(a)

inflammable

(b)

non-combustible

(c)

heavy

(d)

light

7. L.P.G is a mixture of

(a)

methane and propane

(b)

propane and butane

(c)

butane and methane

(d)

none of these

8. Ajay stands 1 m in front of a mirror. He moves 50 cm forward towards the mirror. The distance between Ajay and his image is

(a)

50cm

(b)

2 m

(c)

3 m

(d)

1 m

9. To see your face in a mirror inside a dark room you should shine light from a torch on to

(a)

the mirror

(b)

(c)

the nearest wall

(d)

the ceiling of the room

10. The sun gives us ----------- of heat energy per second.

(a)

1 joule

(b)

3.8$\times$1026 joule

(c)

100 joule

(d)

2.6$\times$1038 joule

11. II. Fill in the blanks

5 x 1 = 5
12. A network of interlinked food chains is called a---------------

()

food web

13. The living components are------- and-------------

()

plants, animals

14. The amount of heat energy liberated by completely burning 1 kg of fuel is called_____
(calorific value / flame value)

()

calorific value

15. In a cinema, the image on the screen is a _____________ (real image / virtual image)

()

real image

16. White light is composed of colours-------------

()

seven

17. III. Answer any 10 in the following

10 x 2 = 20
18. Define Combustion.

19. Discuss the effects of deforestation on the following:
a) Wild animals
b) Environment

20. Match the following types of forests with their unique characteristic features.
Rain forest, Savannah, Desert, Grassland, Taiga, Tundra.

 S.No. Characteristic feature Types of Forest 1. Frequent forest fire 2. Windy weather 3. Snow and ice 4. Hot days and cold nights 5. Ice covered frozen soil 6. Plentiful rainfall
21. a) Why has urbanisation occurred? List the ways in which urbanisation
i) benefits human
ii) harmful to wild life.
b) Suggest one way in which the effects of urbanisation can be reduced.

22. Advise class leaders on water conservation in your school. You can give them the following instructions;

23. Magesh and Keerthivasan were doing an experiment in which water was to be heated in a beaker. Magesh placed the beaker close to the wick in the yellow region of the flame. Keerthivasan placed the beaker on the outer most blue region of the flame. Which beaker would get heated faster?

24. Write a note on gaseous fuels ..

25. Vijay wanted to help his mother who is a doctor to sterilize her instruments. So he washed her clinical thermometer in boiling water. Unfortunately, it broke. What was his mistake?

26. Write a detail account on the Minjur desalination plant

27. Debate on the following topics
Carbon dioxide is necessary for photosynthesis but it causes global warming.

28. What is the basic difference between a concave .and convex mirror.

29. IV. Answer any five in detail :

5 x 5 = 25
30. Write the about importance of forests?

31. What is Rain Water'Harvesting? Write its advantages.

32. Compare the characteristics of the following fuels and choose the best fuel on the basis of the responses to the following questions.
i) Coal ii) Kerosene iii) LPG
Is it easily available?

33. Compare the characteristics of the following fuels and choose the best fuel on the basis of the responses to the following questions.
i) Coal ii) Kerosene iii) LPG
How much does it cost?

34. You are given samples of different kinds of mirrors. Suggest a simple method to identify them.