Class 7 Geography Chapter 4 Air Extra Questions and Answers
Class 7 Geography Chapter 4 Air extra questions and answers available here. Solving class 7 extra questions help students to revise the Chapter most competently. We prepared these questions as per the latest NCERT book and CBSE syllabus. Practicing these extra questions before the exam will ensure excellent marks in the exam.
Air Class 7 Geography Extra Questions and Answers
Very Short Extra Questions and Answers
1. In which layer of the atmosphere do aeroplanes fly?
2. Where do meteors burn up in the atmosphere?
3. What is atmosphere?
Answer: Our earth is surrounded by a huge blanket of air called atmosphere.
4. What is the instrument that measures the amount of rainfall?
Answer: Rain Gauge
5. What is the instrument that measures the atmospheric pressure?
6. What is the wind vane used for?
Answer: Wind Vane shows the direction of the wind.
7. Which layer of the atmosphere makes radio communication possible?
8. Name the instrument which measures temperature.
9. What is the standard unit of measurement for temperature?
Answer: The standard unit of measuring temperature is degree Celsius.
10. Who invented the celsius scale of temperature?
Answer: It was invented by Anders Celsius.
11. What is the freezing and boiling point of water in celsius?
Answer: On the Celsius scale the water freezes at 0°C and boils at 100°C.
12. What is weather?
Answer: Weather is hour-to-hour or day to day condition of the atmosphere.
13. Which gas protects us from harmful sun rays?
Answer: Ozone protects us from the harmful effect of the sun rays.
14. Which layer of the atmosphere is free from clouds?
Answer: Stratosphere layer is almost free from Clouds.
15. What is rain?
Answer: Precipitation that comes down to the earth in liquid form is called rain.
16. What is loo?
Answer: The hot and dry local wind of northern plane of India is called loo.
17. Why do green plants use carbon dioxide?
Answer: Green plants use carbon dioxide to make their food and release oxygen.
18. What is the role of the ozone layer?
Answer: Ozone layer protects us from the harmful effect of the sun rays.
19. What is temperature?
Answer: The degree of hotness and coldness of the air is known as temperature.
20. What is insolation?
Answer: Insolation is the incoming solar energy intercepted by the earth.
21. Why is there no air pressure on moon?
Answer: On the moon there is no air and hence no air pressure.
22. What is humidity?
Answer: Moisture in the air at any time is known as humidity.
23. What is wind?
Answer: The movement of air from high pressure area to low pressure areas is called wind.
24. Why do we feel uncomfortable on a humid day?
Answer: Sweat from our body does not evaporate easily, making us feel very uncomfortable.
25. What do you understand by climate of a place?
Answer: The average weather condition of a place for a longer period of time represents the climate of a place.
26. In which layers of the earth’s atmosphere does the temperature rises very rapidly with increasing height?
Answer: In thermosphere temperature rises very rapidly with increasing height.
27. What causes flooding of low lying areas?
Answer: When trees on hill sides are cut, rainwater flows down the bare mountains and can cause flooding of low lying areas.
28. How are winds named?
Answer: A wind is named after the direction from which it blows, e.g. the wind blowing from the west is called westerly.
29. Which two gases make the bulk of the atmosphere?
Answer: Nitrogen and oxygen are two gases which make up the bulk of the atmosphere.
30. Which gas creates greenhouse effect in the atmosphere?
Answer: Carbon dioxide released in the atmosphere creates a greenhouse effect in the atmosphere.
Short Extra Questions and Answers
1. Name three types of rainfall.
Answer: On the basis of mechanism, there are three types of rainfall: the convectional rainfall, the orographic rainfall and the cyclonic rainfall.
2. What is air pressure?
Answer: Air pressure is defined as the pressure exerted by the weight of air on the earth’s surface.
3. What are the three main types of winds?
Answer: Winds can be broadly divided into three types: Permanent winds, Seasonal winds and Local winds.
4. How does carbon dioxide create greenhouse effect?
Answer: Carbon dioxide released in the atmosphere creates a greenhouse effect by trapping the heat radiated from the earth.
5. Why does hot air rise & cold air sink?
Answer: When air is heated, it expands, becomes lighter and goes up. Cold air is denser and heavy. That is why it tends to sink down.
6. Why wet clothes take longer time to dry on a humid day?
Answer: Wet clothes take longer time to dry on a humid day because the air has a plenty of water vapor already present in it and is not able to accommodate more water vapor.
7. What is global warming?
Answer: When the level of carbon dioxide increases in the atmosphere due to factory smoke or car fumes, the heat retained increases the temperature of the earth. This is called global warming.
8. Why poles are covered with snow?
Answer: The amount of insolation decreases from the equator towards the poles. Therefore, the temperature decreases in the same manner. That’s why poles are covered with snow.
9. Why rain is important for us? How plants can help with water conservation?
Answer: Most of the ground water comes from rainwater. Plants help preserve water. When trees on hill sides are cut, rainwater flows down the bare mountains and can cause flooding of low lying areas.
10. How do bacteria help plants use nitrogen?
Answer: Plants need nitrogen for their survival. They cannot take nitrogen directly from the air. Bacteria that live in the soil and roots of some plants take nitrogen from the air and change its form so that plants can use it.
11. Why is the greenhouse effect important?
Answer: Carbon dioxide released in the atmosphere creates a greenhouse effect by trapping the heat radiated from the earth. It is therefore called a greenhouse gas and without it the earth would have been too cold to live in.
12. Why amount of insolation decreases from equator towards poles?
Answer: Sun rays falls almost vertically on the equator and covers less space whereas sun rays falls at slanting angle on the poles and covers more space. Thus, the amount of insolation decreases from the equator towards the poles.
13. How air circulation takes place?
Answer: When air is heated, it expands, becomes lighter and goes up. Cold air is denser and heavy. That is why it tends to sink down. When hot air rises, cold air from surrounding area rushes there to fill in the gap. That is how air circulation takes place.
14. Air above us presses us with a great force on our bodies. However, we don’t even feel it. Why?
Answer: Air above us presses us with a great force on our bodies. However, we don’t even feel it. This is because the air presses us from all directions and our body exerts a counter pressure.
15. Why do astronauts wear space suits on the moon?
Answer: Astronauts have to wear special protective space suits filled with air when they go to the moon. If they did not wear these space suits, the counter pressure exerted by the body of the astronauts would make the blood vessels burst. The astronauts would bleed.
Long Extra Questions and Answers
1. Why temperature in cities much higher than that of villages?
Answer: Temperature in cities is much higher than that of villages because
- The concrete and metals in buildings and the asphalt of roads get heated up during the day. This heat is released during the night.
- Also, the crowded high rise buildings of the cities trap the warm air and thus raise the temperature of the cities.
2. Why is the atmosphere essential for life?
Answer: All living beings on this earth depend on the atmosphere for their survival. It provides us the air we breathe and protects us from the harmful effects of the sun’s rays. Without this blanket of protection, we would be baked alive by the heat of the sun during day and get frozen during night. So it is this mass of air that has made the temperature on the earth liveable.
3. What are the harmful effects arising from the greenhouse effect?
Answer: When its level in the atmosphere increases due to factory smoke or car fumes, the heat retained increases the temperature of the earth. This is called global warming. This rise in temperature causes the snow in coldest parts of the world to melt. As a result the sea level rises, causing floods in the coastal areas. There may be drastic changes in the climate of a place leading to extinction of some plants and animals in the long run.
4. Discuss the importance of stratosphere?
Answer: Importance of stratosphere are:
- Above the troposphere lies the stratosphere. It extends up to a height of 50 km. This layer is almost free from clouds and associated weather phenomenon, making conditions most ideal for flying aeroplanes.
- One important feature of stratosphere is that it contains a layer of ozone gas which protects us from the harmful effect of the sun rays.
5. What is the composition of the atmosphere?
Answer: The air we take in while breathing is actually a mixture of many gases. Nitrogen (78%) and oxygen (21%) are two gases which make up the bulk of the atmosphere. Carbon dioxide (O.3%), helium, ozone, argon (0.93%) and hydrogen are found in lesser quantities. Apart from these gases, tiny dust particles are also present in the air. The pie chart gives you the percentage of different constituents of air.
6. Write a short note on the distribution of air pressure in atmosphere?
Answer: Air pressure is defined as the pressure exerted by the weight of air on the earth’s surface. As we go up the layers of atmosphere, the pressure falls rapidly. The air pressure is highest at sea level and decreases with height. Horizontally the distribution of air pressure is influenced by temperature of air at a given place. In areas where temperature is high the air gets heated and rises. This creates a low-pressure area. Low pressure is associated with cloudy skies and wet weather.
7. What are the different types of winds?
Answer: Winds can be broadly divided into three types.
(i) Permanent winds – The trade winds, westerlies and easterlies are the permanent winds. These blow constantly throughout the year in a particular direction.
(ii) Seasonal winds – These winds change their direction in different seasons. For example: monsoons in India.
(iii) Local winds – These blow only during a particular period of the day or year in a small area. For example: land and sea breeze and loo.
8. How does nature maintain a balance of oxygen and carbon dioxide in the atmosphere? What is the result of this balance get disturbed?
Answer: Oxygen is the second most plentiful gas in the air. Humans and animals take oxygen from the air as they breathe. Green plants produce oxygen during photosynthesis. In this way oxygen content in the air remains constant. If we cut trees then this balance gets disturbed. Carbon dioxide is another important gas. Green plants use carbon dioxide to make their food and release oxygen. Humans or animals release carbon dioxide. The amount of carbon dioxide released by humans or animals seems to be equal to the amount used by the plants which make a perfect balance. However, the balance is upset by burning of fuels, such as coal and oil. They add billions of tons of carbon dioxide into the atmosphere each year. As a result, the increased volume of carbon dioxide is affecting the earth’s weather and climate.
9. Write a short note on different layers of atmosphere.
Answer: Our atmosphere is divided into five layers starting from the earth’s surface
(i) Troposphere: This layer is the most important layer of the atmosphere. Its average height is 13 km. The air we breathe exists here. Almost all the weather phenomena like rainfall, fog and hailstorm occur in this layer.
(ii) Stratosphere: Above the troposphere lies the stratosphere. It extends up to a height of 50 km. This layer is almost free from clouds and associated weather phenomenon, making conditions most ideal for flying aeroplanes.
One important feature of stratosphere is that it contains a layer of ozone gas which protects us from the harmful effect of the sun rays.
(iii) Mesosphere: This is the third layer of the atmosphere. It lies above the stratosphere. It extends up to the height of 80 km. Meteorites burn up in this layer on entering from the space.
(iv) Thermosphere: In thermosphere temperature rises very rapidly with increasing height. Ionosphere is a part of this layer. It extends between 80 400 km. This layer helps in radio transmission. In fact, radio waves transmitted from the earth are reflected back to the earth by this layer.
(v) Exosphere: The upper most layer of the atmosphere is known as exosphere. This layer has very thin air. Light gases like helium and hydrogen float into the space from here.