The Class 7 is an important year in a student’s life and Science is one of the subjects that require dedication, hard work, and practice. It’s a subject where you can score well if you are well-versed with the concepts, remember the important formulas and solving methods, and have done an ample amount of practice. Worry not! Home Revise is here to make your Class 7 journey even easier. It’s essential for students to have the right study material and notes to prepare for their board examinations, and through Home Revise, you can cover all the fundamental topics in the subject and the complete NCERT Class 7 Science Book syllabus.
Exercise Questions
1. Fill in 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.
Solution:
(a) Wind is moving air.
(b) Winds are generated due to uneven heating on the earth.
(c) Near the earth’s surface, warm air rises up, whereas cold air comes down.
(d) Air moves from a region of high air pressure to a region of low air pressure.
2. Suggest two methods to find out wind direction at a given place.
Solution:
The two methods to finding out the wind direction at a given place are as follows:
i. By seeing the direction of dry leaves released in the air.
ii By seeing the direction in which it is difficult to ride the bicycle.
3. State two experiences that made you think that air exerts pressure (other than those given in the text).
Solution:
i. When we fill the air in the balloon, it becomes tight, and if we try to fill more air, the balloon will burst which proves air exerts pressure.
ii. Wind causes curtains, doors and windows to move with the direction of the wind. This demonstrates air exerts pressure.
4. You want to buy a house. Would you like to buy a house having windows but no ventilators? Explain your answer.
Solution:
It is not a good idea to buy a house without ventilators because warm air is lighter than cold air hence warm air passes out of your home through ventilators. Accordingly, without ventilators, warm air will not pass out, and the house will remain warm.
5. Explain why holes are made in hanging banners and hoardings.
Solution:
Holes in the banners and hoardings help air to pass through them. Hence, banners can withstand the pressure of the air and remains intact.
6. How will you help your neighbours in case a cyclone approaches your village/town?
Solution:
We can help our neighbours in case of a cyclone approaches by any of the following measures:
7. What planning is required in advance to deal with the situation created by a cyclone?
Solution:
8. Which one of the following places is unlikely to be affected by a cyclone?
(i) Chennai
(ii) Mangaluru (Mangalore)
(iii) Amritsar
(iv) Puri
Solution:
The answer is (iii) Amritsar because Amritsar is far away from the sea, while the remaining three are coastal areas and are more likely to be hit by a cyclone.
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.
Solution:
The answer is (i) In winter, the winds flow from the land to the ocean.