Here in this post we provided NCERT Exemplar Problem Class 7 Science Wind, Storm and Cyclone Chapter 7 Full Explanation by group of Science Experts. We have provided here each questions answer with reason behind the answer.
Hope it help you!
Wind, Storm and Cyclone Class 7 Exemplar full Explanation:
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Multiple Choice Questions
1) A fire alarm usually detects smoke in case of fire. Where should such an alarm be placed in a room ?
a) Near the door
b) On the floor
c) On any wall
d) On the ceiling
Answer:- d) on the ceiling
Fire alarm should be on ceiling because the smoke of fire gets upward earlier as compared to the sides of the walls of room.
2) Four schematic diagrams are shown in figure 8.1 depict the direction of sea breeze. Which of them gives the correct direction ?
Answer:- c)
Figure C shows the correct direction of the sea breeze.
3) Figure 8.2 shows a child blowing air with a straw near the opening of another straw which has its other end in a soft drink bottle. It was observed that the level of the soft drink in the straw rises up as soon as air is blown over its open end. Which one of the following best explains the reason for rise in level of the drink?
A) Blowing of air decrease pressure over the opening of the straw.
B) The straw of the soft drinks bottle collapse when air is blown over its open end.
C) Blowing of air warms up the air inside the straw.
D) Blowing of air increase the pressure on the surface of soft drink in the bottle.
Answer:- a) Blowing of air decrease pressure over the opening of the straw .
At the opening of the straw pressure is decreased on blowing of air and thus the soft drinks comes upward direction.
4) Following are precautions one must take in case a Strom is accompanied by lightning .
Do not take shelter under a tree.
Do not take shelter under an umbrella with a metallic end.
III. Do not take shelter in open garages, storage sheds, etc.
Do not take shelter in a bus in the open.
Which of these is not correct?
A)i) B) ii)
C) iii) D) iv)
Answer:- d) iv) Do not take shelter in a bus on the open.
Do not take shelter in a bus on the open is incorrect among the above. As we must take shelter in the car or bus as it is a safer place in the Strom accompanied by lightning.
5) Which of the following place is most likely to be affected by a cyclone?
A) Mumbai
B) Puri
C) Goa
D) Porbandar
Answer:- b) puri
Among the above puri is most likely to be affected by the cyclone.
6) A curtain is hanging at the entrance of a room. A long corridor runs at right angles to the door. That is parallel to the curtain. If a strong wind blows along the corridor, the curtain will
a) Get pushed inside the room.
b) Get pushed outside the room.
c) Get collected towards one end / swirled.
d) Remain unaffected.
Answer:- b) Get pushed outside the room.
Curtain will pushed outside the room in this situation.
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Very Short Answer Questions
7) Why is Chandigarh unlikely to be affected by a cyclone?
Answer:- the process of formation of cyclone is a complex process. Primarily thunderstorm is formed in the hot , Humid, tropical areas. When the temperature rises it produces Strong upward rising winds. Winds carry water droplets along with them which goes upwards and freezes and fall down again. Falling water droplets along with the high wind which creates lightning and sound which is known as thunderstorm. When there is drop in pressure and high speed wind that weather condition is known as cyclone. But Chandigarh is the place where there is no sea or ocean nearer to it. Therefore it is not likely to be affected by the cyclone.
8) Name the ocean which is mainly responsible to bring rain bearing monsoon winds to Kerala coast in June every year?
Answer:- the ocean which is mainly responsible to bring rain bearing monsoon winds to Kerala coast in June every year is The Indian Ocean. The whole coastline of the India is mostly affected by the cyclone. Mainly the east coast. The west coast is less affected by the cyclone storms as compared to the east coast due to less intensity and frequency of the cyclones in that area.
9) Fill in the blanks :
I) Air around us exerts _________.
Answer:- Air around us exerts pressure.
II) The moving air is called _________.
Answer:- The moving air is called Wind .
III) the main cause of wind movement is uneven ____________on the earth.
Answer:- The main cause of the wind movement is uneven heating on the earth.
IV) High speed wind can cause cyclone in regions of _________ pressure.
Answer:- High speed wind can cause cyclone in regions of low pressure.
10) State whether the following statements are true or false.
I) If wind flows from land to the ocean, then it is daytime.
Answer:- False
If wind flows from Ocean to the land , then it is daytime.
II) A very high pressure system, with very high speed wind surrounding it forms a cyclone.
Answer:-. False
A very low pressure system, with very high speed heavy wind surrounding it forms a cyclone.
III) The coast line of the India is not vulnerable to cyclone.
Answer:-False
The coast line of India is very vulnerable to cyclone.
IV) Warm air is lighter than cool air.
Answer:- True.
11) To expel hot air out of the Kitchen. ‘A’ has an exhaust fan fitted on the window of her kitchen and ‘B’ has a similar exhaust fan fitted on the wall near the ceiling of her kitchen . Which of the exhaust fan will expel the hot air more effectively? Explain why?
Answer:- Exhaust of B will expel the hot air more effectively than the exhaust of A. As the hot air are become lighter and goes upwards . As the B has its exhaust fan on the greater height than A the hot air which is risen up will expel more effectively.
12) Why is it advisable not to shut all the doors and windows during a Strom?
Answer:- It is advisable not to shut all the doors and windows during the storm Because there should one exhaust for the wind inside the room otherwise the roof can be blown away due to the low pressure created by the strong and heavy wind.
13) A flat in Mumbai with a balcony facing the sea has some clothes hung on clothes line in the balcony. Towards which direction the clothes will be blown in the afternoon? Explain.
Answer:- The flat is in Mumbai with a balcony facing the sea. The clothes will be blown towards the house in the afternoon because in the afternoon the land is more heat up than the water in the sea thus the wind blows from the sea water to the land . Thus the clothes will be blown towards the house in afternoon.
14) Figure. 8.3 shows a diagrammatic representation of trees in the afternoon along a sea coast. State on which side is the sea ; A or B ? Give reasons for your choice .
Answer:-In the given picture, trees are given along the sea coast line. Since In the afternoon due to the sun the Land is more heated than the water in the sea. Therefore in the afternoon the sea breeze are blown from sea to land. Therefore the sea it at the side B.
15) A flag mounted on a flag post near the sea coast flutters in the direction of sea . At what time of the day does this happen – at midnight or in the afternoon?
Answer:- A flag mounted on a flag post near the sea coast line flutters in the direction of sea. From these sentences it is clear that the timing of the day is midnight. Because in the midnight the air blows towards the sea from the land. Exactly as opposite to the afternoon in the afternoon wind blows from the sea to the land . thus it is the midnight when the flag flutters in the direction of sea.
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Short Answer Questions
16) Match column I with column II. There can be more than one match.
Column I | Column II |
A)On heating air | I) descends |
B)on cooling air | II) expands |
III) contracts | |
IV)rises |
Answer:-
A) On heating air –
ii) expands
iv) rises
B) On cooling air –
i) descends
iii) contracts
17) Paheli kept an empty bottle made of plastic inside a refrigerator. After few hours , when she opened the refrigerator she found the bottle has collapsed. Explain the possible reason.
Answer:- The empty bottle made up of plastic when the kept in refrigerator after few hours collapsed due to the high pressure of the outside the bottle and low pressure Inside the bottle. The pressure inside the bottle was low and therefore the bottle collapsed .
18) When strong / high speed wind blows, an umbrella held upright at times gets upturned. Explain the reason.
Answer:-when strong or high speed wind blows it creates an low pressure when passing over the open umbrella . Thus due to the low pressure Created by the high speed wind the umbrella upturned sometimes.
19) Suggest some precautions to be taken to prevent the roof of a tin sheet from flying away during a fierce wind Strom.
Answer:-
Precautions to be taken in the wind Strom are as we can put the heavy stones over the tin sheet thus due to the weight of the big stone tin will not blow . Further we can do one more thing that we can tight the tin with screw over the heavy iron pipe thus the wind cannot blow away tin sheet along with it.
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Long Answer Questions
20) Describe an activity to demonstrate that warm air is lighter than cool air .
Answer:- An activity to demonstrate that warm air is lighter than cool air is as below :-
A) Take two empty paper bags.
B) Hang both of the bags in inverted position, with the help of a metal or wooden stick.
C) Tie the middle portion of the stick with thread.
D) Hold the stick with the thread titled with balance.
E) Keep a burning candle below one bag and now observe what happened.
F) the balance of bags is disturbed.
G) Warm bag goes downwards and the cool bag goes upwards.
H) These is because the on heating the gets expand and occupies more space.
I) When the same thing occupies more space it gets lighter than before.
J) Therefore the warm air is lighter than the cold air.
K) Thus these activity shows that warm air is lighter than cool air.
21) The picture in figure. 8.4 shows tree line along the sea coast on an island near the equator. As shown , the tree tops are permanently bent in one direction. Are the trees bent towards the sea or away from it ? Explain.
Answer:- In the figure 8.4 there is tree line along the sea coast on an island near the equator. In the picture it is clearly seen that the picture is of day time. In the day time the sea breeze are blown from sea to the land . Thus the trees tops are bent in one direction that is it slightly bended towards the land.
22) Identify the names of six natural phenomena from the following word diagram given as figure. 8.5.
Answer:-