NCERT Solutions for class 7 Science Chapter-8

NCERT Solutions for  class 7 Science Chapter-8

Winds I Storms and Climate

Q1. Fill the missing word in the blank spaces in the following statements:

(a) Wind is —- moving —- air .

(b) Winds re generated due to —- uneven —- heating on earth.

(c) Near the earth’s surface  —- warm —- air rises up whereas —- cooler —- air comes down.

(d) Air moves from a region —- high —- of pressure to a region —- low —- of pressure.

Q2. Suggest  two methods to fine out wind direction at a given place.

Ans. (i) Take a piece of a paper in your hand. Allow to fall from your hand. It will flow in the direction in which wind is blowing.

(ii) You can also use a wind – pane which helps us know accurate wind direction.

Q3. State two experiences that made you think that air exerts pressure.

Ans. (i) Balloons and balls can be used only when they are inflated with air. When balloon is overfilled with air bursts due to excessive air pressure.

(ii) C ompressed air is used in the brake system for stopping trains.

Q4. You want  to buy a house. Would you like to buy a house having window but no ventilators? Explain your answer.

Ans. No, a house which has no ventilators is not a safe or healthy house to live in. The air circulation is not there in such a house. So, it has no fresh air. Because warm air rises up and goes out  through ventilators and fresh air comes in through window.

Q5. Explain why holes are made in hanging banners and hoardings.
Ans. Air exerts pressure. Due to this pressure banners and hoarding flutter and torn when wind is blowing fast. Holes are made in banners and hoardings so that wind passes through the holes and they do not become loose and fall down.

Q.6.How will you help your neighbours in case cyclone approaches your village/town?
Ans. (i) I will make them aware of cyclone forecast and warning service.
(ii) Rapid communication of warning to the government agencies and all the important places.
(iii) Construction of cyclone shelters in the cyclone prone areas.
(iv) Helping them to shift essential goods, domestic animals etc. to safer places

Q.7.What planning is required in advance to deal with the situation created by a cyclone?
Ans.To deal with cyclone, it is important to follow the following points :
(i) carefully listening the warnings transmitted on T.V. and radio.
(ii) moving to the safer places.
(iii) keeping an emergency kit ready.
(iv) store food in waterproof bags. .
(v) not venturing into sea.
(vi) keeping all the emergency numbers.

Q.8. Which one of the following places is unlikely to be affected by cyclone?
(i) Chennai (ii) Mangalore
(iii) Amritsar (iv) Puri
Ans.(iv) Amritsar

Q.9.Which of the statements given below is correct?

(i) In winter the winds flow from the land to the ocean.
(ii) In summer the winds flow from the land towards the ocean.
(iii) A cyclone is formed by a very high-pressure system with very high-speed winds revolving around it.
(iv) The coastline of India is not vulnerable to cyclones.
Ans.(i) In winter the winds flow from the land to the ocean.

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