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Geography [3 Mark Question Answer]

Composition and Structure of the Atmosphere · ICSE STD 9 (ICSE - English Medium). 4 questions.

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[3 Mark Question Answer]

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4 questions · timed · auto-graded

Question 13 Marks
Mention any three functions of the atmosphere.
Answer
  1. Air has weight and exerts pressure. Being pressed down it always remains in contact with land and water.
  2. Due to their physical contact, the exchange of gases between air, land, and water takes place on a continuous basis.
  3. Soil absorbs oxygen and nitrogen due to this contact. Water vapours in air rise from oceans on account of evaporation.
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Question 23 Marks
What are the properties of Ionosphere?
Answer
Properties of Ionosphere :
  1. It extends from 80 km to 480 km.
  2. It contains electrically charged gas molecules which reflect the radio waves used in long-distance communication back to the earth.
  3. The northern lights or aurora borealis are in this zone,
  4. The temperature in this layer rises to a very high degree because the molecules in this layer absorb X-rays and ultraviolet radiation coming from the sun.
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Question 33 Marks
Why should we protect the atmosphere?
Answer
Atmosphere is necessary to sustain life on earth because without atmosphere there would be no oxygen, no weather changes, rainfall, etc, which are essential for activities of human life and ideal temperature on the earth.
The atmosphere protects the earth from harmful ultraviolet and infrared rays of the sun. It has oxygen and nitrogen, the life-sustaining gases. It helps in retaining the necessary warmth on the earth and helps in the circulation of water vapour as the source of rainfall. These functions of the atmosphere keep it in a dynamic state.
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Question 43 Marks
$\text{CFCs} $
Answer
$\text{CFCs} :\  ($Chlorofluorocarbons$)$ are organic compounds that contain carbon, chlorine, fluorine produced as volatile derivatives of methane and ethane which catalyze the conversion of ozone $(O_3)$ into $O_2,$ while $O_3$ is more powerful to absorb ultra$-$violet rays than that of $O_2.$ So $\text{CFCs}$ disturb the ozone layer which is so essential for the earth.
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[3 Mark Question Answer] - Geography STD 9 Questions - Vidyadip