NCERT solutions for Class 7 Science have been provided below to aid the students with answering the questions correctly, using a logical approach and methodology. CBSE Class 7th Science solutions provide ample material to enable students to form a good base with the fundamentals of the NCERT Class 7 Science textbook.
Q.1.Fill the missing word in the blank spaces in the following statements:
(a) Wind is ___________air.
(b) Winds are generated due to _________ heating on the earth.
(c) Near the earth’s surface _________ air rises up whereas _________ air comes down.
(d) Air moves from a region _________of pressure to a region _________of pressure.
Ans.(a) moving (b) uneven
(c) warm, cooler (d) high, low
Q.2. Suggest two methods to find out wind direction at a given place.
Ans.(i) Take a piece of a paper in your hand. Allow it 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 to know accurate wind direction.
Q.3.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 it bursts due to excessive air pressure.
(ii) Compressed air is used in the brake system for stopping trains.
Q.4.You want to buy a house. Would you like to buy a house having windows 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 windows.
Q.5.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.