Page 114 - ICSE Chemistry 6

Air pollu on: The release of harmful par cles and gases into the air that have damaging eff ects on
living things and the environment
Air pollutants: Gases and par cles in the atmosphere that harm organisms and aff ect climate
Greenhouse gases: Gases such as methane, carbon dioxide and water vapour that trap heat energy of the
sun
Greenhouse eff ect: The trapping of heat energy of the sun by greenhouse gases present in the earth's
atmosphere
Global warming: The increase in the average temperature of the earth's atmosphere, especially a
sustained increase which is great enough to cause changes in the global climate
Acid rain: Rain containing harmful chemicals from gases like nitrogen oxides and sulphur oxides
that damages trees, crops, animals and buildings

Quick Review

• Air is present everywhere around us.
• The presence of atmosphere makes life possible on the earth.
• Atmosphere is the layer of air that surrounds the earth.
• Air is a mixture of gases. Air is made up of nearly 78% nitrogen, 21% oxygen, 0.9% argon, 0.04%
water vapour, 0.03% carbon dioxide and the remaining 0.03% are the other trace gases.
• Air also contains suspended dust par cles and smoke.
• Nitrogen does not support combus on. It is needed by plants to grow.
• The presence of oxygen is essen al for survival of living organisms. It is also required for combus on.
• Carbon dioxide is also important for sustenance of life. Plants need carbon dioxide for
photosynthesis. Human beings and animals take in oxygen from the atmosphere and release carbon
dioxide during breathing. The concentra on of carbon dioxide in the atmosphere aff ects the global
temperature.
• Water vapour are also present in the atmosphere. They are formed due to evapora on and boiling of
water.
• Air also contains suspended dust par cles and smoke.
• The balance between the levels of oxygen and carbon dioxide in the atmosphere is maintained by
two processes—respira on and photosynthesis.
• Air pollu on can be harmful for our survival. We must take adequate steps to control it.

EXERCISES

BE PROMPT

A. Fill in the blanks.

1. Air exerts equal ___________ in all direc ons.
2. All animals and plants need ____________ for respira on.
3. Solid carbon dioxide is called _____________.

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