Points to Remember, Glossary, Concept Map

Points to Remember

• Oxygen exists in nature as silicates, carbonates, oxides and water. It also exists in free state as part of air in the atmosphere.

• Oxygen is a colourless and odourless gas. It dissolves sparingly in water. It is denser than air.

• Metals like magnesium, iron and sodium burn in oxygen and give basic oxides.

• Bacteria convert atmospheric nitrogen directly into soluble nitrogen compounds.

• Though nitrogen is inactive at ordinary condition, it combines with many elements at high temperature and pressure or in the presence of catalyst.

• Carbon dioxide cannot exist as a liquid at atmospheric pressure. It occurs as carbonates in nature.

• Carbon dioxide is acidic in nature and turns lime water milky. It is used in fire extinguisher.

• Global warming refers to an average increase in the temperature of the atmosphere or simply it is the warming of the earth.

• The green house gases are carbon dioxide, methane, nitrous oxide, chlorofluoro carbons, etc.

GLOSSARY

1. Atmosphere Gaseous jacket that surrounds the earth.

2. Fixation of nitrogen Process that converts nitrogen in the air into a nitrogen compounds.

3. Global warming An average increase in the temperature of the atmosphere.

4. Green house effect Trapping of radiation from the sun by green house gases in the atmospherethat leads to rise in the earth’s atmospheric temperature.

5. Haber’s process Synthesis of ammonia from nitrogen and hydrogen with the help of catalyst­ under 500 atm pressure and 550˚C temperature.

6. Oxygenes A Greek word meaning ‘acid producers’ from which the name ‘Oxygen’ is derived.

7. Soda water A form of water produced when carbon dioxide is dissolved in water under pressure.

8. Sublimation Process of conversion of solid directly to vapour without reaching liquid state.

Concept Map

REFERENCE BOOKS

1. Environmental Science - Timothy O Riordan Second edition

2. Basic of atmospheric science - A. chandrasekar

3. Text book of Air pollution and its control - S.C. Bhatia

INTERNET RESOURCES

1. www.chemicool.com

2. www.nationgeographic. com

3. www.environmentalpollutioncenters.org

ICT CORNER

AIR

Through this activity you will know about carbon emission, climate change, global average temperature etc.

Step 1

* Open the Browser and type the URL given below.

* Click onany one of the items to know about carbon emission, climate change, global average temperature, sea level etc.

* For example, click on the “Climate Time Machine” a popup screen will open. In that you can able to see carbon emission global average sea level, temperature, sea ice etc.

* When you click global average sea level, you will find year wise sea level.

Browse in the link:

https://climatekids.nasa. gov/menu/play/