NCERT Exemplar for Class 7 Science Solutions Chapter 8 Wind, Storm and Cyclone

Exercise

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

Ans: (d) On the ceiling

Explanation: In the case of a fire, the air on top of the fire heats up and rises. As a result, an alarm should be installed on the ceiling of a room.

2. Four schematic diagrams are shown in Figure 8.1 to depict the direction of sea breeze. Which of them gives the correct direction?

(a)

(b)

(c)

(d)

Ans:  Option is the correct response (c). 

Explanation: During the summer, the earth heats up and the air all across the land rises. This causes the air to blow cooler from the sea toward land. This is referred to as 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 the rise in level of the drink?

                                                                 Fig.18.2

(a) Blowing of air decreases pressure over the opening of the straw. 

(b) The straw of the soft drink bottle collapses when air is blown over its open end. 

(c) Blowing of air warms up the air inside the straw. 

(d) Blowing air increases the pressure on the surface of the soft drink in the bottle.

Ans: (a) Blowing of air decreases pressure over the opening of the straw. 

Explanation: Blowing air reduces pressure over the opening of the straw in the given condition.

4. Following are precautions one must take in case a storm is accompanied by lightning. 

(i) Do not take shelter under a tree. 

(ii) Do not take shelter under an umbrella with a metallic end.

(iii) Do not take shelter in open garages, storage sheds, etc. 

(iv) Do not take shelter in a bus in the open. 

Which one of these is not correct? 

(a) (i) 

(b) (ii) 

(c) (iii) 

(d) (iv)

Ans: (d) (iv) Do not take shelter in a bus in the open. 

Explanation: As we know, buses are made of metals from the outside, so when lighting strikes the bus, it has no effect on the inside, and it doesn't matter what lighting does to the outside part of the bus, but for extra knowledge, the real reason is lighting is static electricity, which is different from the electricity in our homes, lighting has no effect on the inside of a hollow closed conductor but has an effect on the outside.

5. Which of the following places is most likely to be affected by a cyclone? 

(a) Mumbai 

(b) Puri 

(c) Goa 

(d) Porbandar

Ans: (b) Puri 

Explanation: As we all know, the east coast is more likely to meet cyclones with greater speed (intensity) and quantity of cyclones than the west coast, and all other places save Puri are on the west coast, whereas Puri is on the east coast.

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.

Ans: (b) get pushed outside the room. 

Explanation: Because high-speed winds have low pressure due to particle scattering, and because one side of the curtain has low pressure and the other side has high pressure, the winds will flow from high-pressure area to low-pressure area in order to maintain balance, as we already know, and thus the curtain will be pushed in the direction of the high-pressure wind.

VERY SHORT ANSWER TYPE QUESTIONS

7. Why is Chandigarh unlikely to be affected by a cyclone?

Ans: Because it is bordered by other states, Chandigarh is unlikely to be harmed by a cyclone because it is not near a coastal line and has no sea or ocean nearby. Cyclones form near coastal places because there are water bodies nearby to initiate the process, and the temperature of that water body must also be appropriate to develop the cyclone.

8. Name the ocean which is mainly responsible for bringing rain bearing monsoon winds to Kerala coast in June every year? 

Ans: Every year in June, the 'Indian Ocean' is primarily responsible for bringing rain-bearing monsoon winds to the Kerala coast.

9. Fill in the blanks. 

(i) Air around us exerts __________ . 

Ans: Air around us exerts pressure

(ii) The moving air is called _________ . 

Ans: The moving air is called wind .

(iii) The main cause of wind movement is uneven ___________ on the earth. 

Ans: The main cause of wind movement is uneven heating on the earth

(iv) High speed wind can cause cyclones in regions of ___________ pressure.

Ans: High speed wind can cause cyclones 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. 

Ans: The given statement is false. It is night when the wind blows from the land to the sea. In comparison to the land, water cools down more slowly at night. As a result, the chilly wind from the land blows toward the sea.

(ii) A very high pressure system, with very high speed wind surrounding it forms a cyclone. 

Ans: The given statement is false. A cyclone is formed by a low-pressure system surrounded by high-speed wind.

(iii) The coastline of India is not vulnerable to cyclones. 

Ans: The given statement is false. India's coast line, particularly the east coast, is vulnerable to cyclones.

(iv) Warm air is lighter than cool air.  

Ans: The given statement is true. Warm air is lighter than cold air because it expands and takes up more space when heated. When something takes up more room, it becomes lighter and smaller. Because warm air is lighter, it rises. The less dense air floats in the thicker air, similar to how ice floats on water because ice is less dense than water.

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 fans will expel the hot air more effectively? Explain why? 

Ans: Warm air rises in 'B's kitchen, and her exhaust fan is at a standard height in comparison to A's. As a result, the heated air will be expelled more effectively.

12. Why is it advisable not to shut all the doors and windows during a storm?

Ans: During a storm, it is not suggested to close all the windows and doors because the wind velocity is extremely strong. This has the potential to inflict significant harm.

13. A flat in Mumbai with a balcony facing the sea has some clothes hung on a clothesline in the balcony. Towards which direction the clothes will be blown in the afternoon? Explain.

Ans: During the afternoon, the ground heats up faster than the water. The air above the ground heats up and rises. This air causes a pressure drop in that area. As a result, the wind from the sea will blow towards the ground. The garments will be blown towards the home as a result of this.

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. 

Ans: In the afternoon, the ground heats up more quickly. The air above the ground heats up and rises. This air causes a pressure drop in that area. As a result, the sea is on side B, while the land is on side A.

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?

Ans: At night, the water cools down more slowly than the land. However, about 2 a.m., a chilly wind blows from the land in the direction of the sea. As a result, the right response is 'mid-night.'

SHORT ANSWER TYPE QUESTIONS

16. Match Column I with Column II. There can be more than one match.

Ans: The correct table is

17. Paheli kept an empty bottle made of plastic inside a refrigerator. After a few hours, when she opened the refrigerator she found the bottle had collapsed. Explain the possible reason.

Ans:  While the air is being cooled, it contracts. Because of the reduced pressure, the air within the bottle compresses. As a result of the outside pressure, the bottle collapses.

18. When strong/high speed wind blows, an umbrella held upright at times gets upturned. Explain the reason. 

Ans: A low pressure is created when a high-speed or strong wind passes through an umbrella. As a result, the pressure on an umbrella increases.

19.  Suggest some precautions to be taken to prevent the roof of a tin sheet from flying away during a fierce wind storm.

Ans: Some precautions are given below, 

(a) Screw it tight. (b) Put heavy stones or other things on it.

LONG ANSWER TYPE QUESTIONS

20. Describe an activity to demonstrate that warm air is lighter than cool air.  

Ans: (i) Take two same sizes of empty paper bags. 

(ii) On the two ends of a wooden stick hang both of the bags in an upturned position.

(iii) In the centre of the stick tie a portion of thread. 

(iv) According to the figure (A), hold the stick by the thread in balance. 

(v) According to the figure (B), place the burning candle below one of the bags.

(vi) Now, you will observe an unbalanced stick. This represents that as the warm/temperate air rises up and it pushes the bag over the candle. 

(vii) Now we can say that when air is heated, it expands and also occupies more space. So, we can conclude that warm air is lighter as compared to 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. 

Ans: Yes, all of the trees in the illustration are bending towards or away from the water. During the day, the wind blows from the sea toward the land. When compared to the water, the land warms up faster this time. As a result, the air above the earth warms up and rises into the sky. As a result, the tops of the bent trees depict the wind's movement from sea to land.

22. Identify the names of six natural phenomena from the following word diagram given as Figure 8.5.

Ans: The names of six natural phenomena: 

(i) HURRICANE 

(ii) TYPHOON 

(iii) TORANDO 

(iv) LIGHTING 

(v) CYCLONE 

(vi) THUNDERSTORM

About NCERT Exemplar Science

NCERT is the premier institution that creates many of the study materials used for national-level boards like the CBSE as well as for competitive exams like the JEE Main and JEE Advanced. 

NCERT Exemplar is a series of workbooks that contain questions based on the topics covered in the regular NCERT textbooks. These workbooks were created to provide students with enough practice questions for them to learn how to apply the concepts they learn in class. The NCERT Exemplar Science workbook is the series that takes care of the questions based on the Science syllabus.

Advantages of Downloading Class 7 NCERT Exemplar Science Chapter 8 Solutions

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