Air Around Us. Chapter Notes | Eureka Plus Class 6: Book Solutions, Notes & Worksheets PDF Download

Introduction

Air is everywhere around us, in soil and water too. It's colorless and odorless, and while we can't see it, we can feel it when the wind blows. The Earth is surrounded by a layer of air called the atmosphere, extending about 600 km above the Earth.

Composition of Air

• Mixture of Gases: Air is a mix of gases - nitrogen (78%), oxygen (21%), carbon dioxide, water vapor, argon, and neon. It also has dust particles and microorganisms. The upper atmosphere has an ozone layer, protecting us from harmful UV rays.
• Air Pollutants: Human-made substances from vehicles and industries spoil air, called air pollutants, harming plants, animals, and humans.

Nitrogen

• Dominant Gas: Contrary to what we need, the air's most abundant gas is nitrogen (78%). Plants and animals can't use it directly.
• Nitrogen Fixation: Certain bacteria convert nitrogen and oxygen from the air into nitrates, which plants use to make proteins. This process is called nitrogen fixation.

Oxygen

• Essential for Life: All living things need oxygen for respiration, where oxygen helps release energy from sugar. Oxygen is also used in combustion (burning).
• Burning Experiment: If a lighted candle is covered with a glass tumbler, it goes out because it uses up all the oxygen inside.

Thank You, Plants!

Oxygen Production: Despite continuous use, oxygen doesn't run out because plants and plant-like microorganisms produce it through photosynthesis, their way of making food.

Carbon Dioxide

• Plant Use: Plants use carbon dioxide during photosynthesis to make their own food, maintaining a balance in the air.
• Carbon Dioxide Production: Animals produce carbon dioxide when breathing and burning things also releases carbon dioxide into the air.

Water Vapour

• Gaseous Water: Water evaporates from ponds, lakes, and oceans, mixing with air as water vapor. Plants also add water vapor through transpiration.
• Weather Effects: Water vapor causes weather conditions like rain, snowfall, dew, and fog.

Dust and Smoke

Particulate Matter: Air contains dust particles, pollen, fibers, ash, coal, and metal particles from industries and vehicles.

Microorganisms

Airborne Microorganisms: Air carries bacteria, fungi, and viruses, some causing diseases like the common cold.

Uses of Air

• Temperature Regulation: Air helps regulate temperature by spreading the sun's heat all over the Earth.
• Ozone Layer Protection: The ozone layer absorbs harmful UV rays from the sun, protecting all living things.
• Pollen and Seed Dispersal: Wind helps disperse pollen grains and seeds, aiding plant reproduction.
• Wind as a Source of Energy: Windmills use the energy in the wind for various purposes, including drawing water and producing electricity.
• Other Practical Uses: Air is used to inflate balls and vehicle tires, apply brakes in trains, assist in parachute movement, and separate husk from grain through winnowing.
• Musical Instruments: Air is used in playing musical instruments like the flute.

Conclusion

Understanding the air around us is crucial as it affects every aspect of life, from the air we breathe to the weather and even the energy we use. The balance in the composition of air is maintained by natural processes and the contributions of various living organisms, emphasizing the interconnectedness of all elements on Earth.