# NCERT Class VII Science Solutions: Chapter 8-Winds, Storms and Cyclones Part 3

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Question 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?

B’s exhaust fan will expel the hot air more effectively because hot air rises up and her fan is at greater height than A’s.

Question 12:

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

To avoid the roof getting blown away due to the low pressure created by heavy wind.

Question 13:

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

The clothes will be blown towards the house due to sea breeze blowing towards the land.

Question 14:

Figure 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.

B as the wind is blowing from the sea to the land.

Question 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?

At night, the water cools down more slowly than the land. So, at mid – night, cool wind from the land moves towards the sea. Therefore, at mid – night the flag mounted on a flag post near the sea, coast flutters in the direction of sea.

Question 16:

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

 Column I Column II On heating air Descends On cooling air Expands Contracts Rises

 Column I Column II On heating air ii Expandsiv Rises On cooling air i Descendsiii Contracts

Question 17:

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

The air inside the bottle contracts due to low temperature hence the bottle collapses due to the outside pressure.

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