Class 7 Geography Chapter 5 Ratna Sagar

 Short answer type questions:-

Q1. What is the importance of carbon dioxide in the atmosphere?

Ans. The carbon dioxide present in the atmosphere is important for the growth of plants.

Q2. Name the different layers of the atmosphere and their extent.

Ans. The different layers of the atmosphere and their extent are as follows:-

        - Troposphere - near poles about 8 km and near equator around 18 km.

        - Stratosphere - From around 15 to 50 km.

        - Mesosphere - From 50 to 80 km.

        - Thermosphere - From 80 to 800 km.

        - Exosphere - from 800 (upper limit is unknown)

Q3. Which layer of the atmosphere is most important for us and why?

Ans. Troposphere is the most important layer because:-

        - all weather phenomena occur in this layer

        - It protects us from excessive heat of the sun and keeps the earth's surface warm at night. 

        - it contains Nitrogen, Oxygen, Carbon dioxide, etc. 

Q4. Explain the main features of the atmosphere.

Ans. The main features of the atmosphere are as follows:-

        - It contains all the Gasses essential for existence of life, like- Oxygen, Nitrogen and Carbon dioxide.

        - It prevents sun's ultraviolet rays from reaching to the earth.

        - Change in weather is due to presence of atmosphere.

Long answer type questions:-

Q1. Describe the main features of the composition of the atmosphere.

Ans. The main features of the composition of the atmosphere are as follows:-

        - Air is the mixture of Gasses, in which nitrogen is 78% and oxygen is 21%, rest 1% contains all the other gasses, like- Argon, Carbon dioxide, Ozone, Hydrogen, etc.

        - Water vapour , dust particles and smoke is present in the lower layer of the atmosphere.

        - Heavier gasses like:- Oxygen, is mostly found near earth surface, with increase in height their concentration decrease.  

Q2. Explain the importance of nitrogen and oxygen in the atmosphere.

Ans. The Nitrogen and Oxygen both are essential for the existence of life on the surface of earth. 

    Nitrogen is required by plants for growth, but it can't be absorbed directly from air, it is converted into compounds which can be absorbed by plants through roots.

     Oxygen is required by living organism to breath, so it is most important for the existence of life on the surface of earth. It is formed in nature by plants through photosynthesis. 

Q3. What are the main features of the troposphere?

Ans. The main features of the troposphere are as follows:-

        - It is the bottom most layer of the atmosphere which only contain water vapour and     dust particle.

        - Weather phenomena like-  the formation of clouds, fog, frost, dew, thunder, lightning,  precipitation, etc., occur in this layer.

        - The temperature in this layer decreases with increasing altitude, at the increase of every 165m the temperature decrease by 1°C. It is called normal lapse rate.

        - It contain 90% of the air in the atmosphere.

Q4. What is the significance of the atmosphere of the earth?

Ans. Significance of the atmosphere of the earth are as follows:- 

         - It contains all the Gasses essential for existence of life, like- Oxygen, Nitrogen and   Carbon dioxide.

        - It prevents sun's ultraviolet rays from reaching to the earth.

        - Change in weather is due to presence of atmosphere.

        - It acts like green house and controls the extremes of temperature during day and night.

        - It shields us from meteors.