DAV Class 7 SST Solution Chapter 4 Air Around Us
DAV School Books Class 7 SST Solution Chapter 4 Air Around Us all Question Answer. DAV Class 7 4th Chapter Air Around Us full Chapter explanation by expert teacher.
DAV School Books Class 7 SST Solution Chapter 4 Air Around Us
Tick the correct option –
1.) In normal Lapse rate, temperature decreases at the rate of 1oC with every
A) 165m Ascend
b) 175m ascend
c) 185m ascend
d) 195m ascend
Ans – A) 165m Ascend
2.) which layer is safe for flying aircrafts ?
a) Troposphere
b) Stratosphere
c) Mesosphere
d) Thermosphere
Ans – b) Stratosphere
3.) The role of ion-particles in the ionosphere is to
a.) absorb ultra violet rays
b.) Enable Wireless communication
c.) Burn meteors
d) Enable rainfall
Ans – b.) Enable Wireless communication
4.) Which one of the following is the main cause of global warming?
a.) Air Pollution
b.) water Pollution
c.) Soil Pollution
d.) Land Pollution
Ans – a.) Air Pollution
5.) Smog Causes
a.) breathing problems
b.) Purification of air
c.) heavy rainfall
d.) reduction in temperature
Ans – a.) breathing problems
D.) Answer the following questions in brief-
1. Name the layers of the atmosphere.
Ans – Atmosphere has four different layers ,such as- Troposphere, Stratosphere, Mesosphere, and Thermosphere.
2.) How do plants absorb nitrogen?
Nitrogen helps plant in their growth and development and they absorb it through the soil.
3.) Importance of Water vapours-
Water vapours in the atmosphere make the atmosphere calm and cold. Again these water vapours help to make cloud after rejoining and later on bring rain on the Earth as a form of tiny droplets or ice by the process of condensing.
4.) Name the different variables of atmosphere.
The different variables of the Atmosphere are – Atmosphere consists with some major gases like Oxygen, Carbon dioxide . Apart from that helium,Argon Nion etc. gases are also present over here. Water vapours ,Dust particles etc. are the other components present in the atmosphere.
5.) What type of climate does India have?
India has tropical monsoon type of climate. It is neither too wet not too dry type of climate. Moderate types of weather we find here.
E.) Answer the following questions –
1.) What is the importance of carbon dioxide and oxygen for living beings?
Importance of Carbon dioxide –
I.) important for balancing the temperature for the earth surface by absorbing the heat from the Sun.
II.) responsible for maintaining the life cycle of the plant.
III.) carbon dioxide is used in the process of photosynthesis to make food for the plants.
Importance of Oxygen-
I.) Oxygen is an important gas for all the living organisms to stay alive
II.) Another name of Oxygen is life supporting Gas.
2.) Name three major sources of pollutants in the air. Also state the ill-effects of these air pollutants.
Three major sources of air pollutants are- Carbon monoxide, Sulphur dioxide and lead particles.
Ill effects of air pollutants are-
I.) making smog which causes several diseases like respiratory problems, several skin diseases etc.
II.) causes air pollution .
III.) causing several diseases.
3.) What is the importance of ozone gas? Why is global warming a threat to life on the earth?
Importance of Ozone Gas-
Ozone gas is found in the stratosphere and the ozone layer acts as a filter by absorbing ultra violet rays coming from the Sun. These rays increase the cancer causing agent. Moreover it acts as an umbrella or a shield of the earth surface.
Global warming is a threat to life because increasing temperature for global warming effects the balance of the earth surface and causes different diseases.
4.) How is rainfall caused? Explain it with the help of a diagram.
Rainfall- hot air of the atmosphere becomes light and go higher where it turns cold and the water presents there condenses into tiny droplets or ice. These tiny droplets become larger by coming together and in course of time become heavier. When the air can not hold them ,come as a form of rain or snow fall according to the temperature of the earth surface.
5.) Write the difference between weather and climate.
Differences between weather and climate –
Both are state of atmospheric condition.
Weather is atmospheric condition of a specific place of a specific time. But climate is a atmospheric condition of a large area for a long period of time. Weather includes temperature, humidity and pressure and Climate includes temperature, rainfall and pressure. Weather can vary in the different places of the same city but climate remains same.
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