Revision: Air Science SSLC (English Medium) Class 8 Tamil Nadu Board of Secondary Education

Rusting: Slow conversion of iron into its hydrated oxide in the presence of moisture and air is called rusting.

Respiration: Respiration is a chemical process that takes place in all living beings (slow in plants). In this process, oxygen present in inhaled air reacts with the digested food material in the body. This results in the release of energy, carbon dioxide, and water.

Sugar + Oxygen → CO2 + Water + Energy.

Photosynthesis: Process of producing food by green plants taking CO2 from the air, water from the soil by roots, and in the presence of sunlight and chlorophyll is called photosynthesis.

Smog : Oxides of nitrogen form a mixture of smoke and fog known as smog which affects our eyes too.

Global warming : An increase in the percentage of carbon dioxide, methane, nitrous oxide and chlorofluorocarbon traps the heat causing the temperature of the earth and its surroundings to rise. This is known as global warming.

Combustion: Combustion also called burning “is burning of substance in the oxygen of air completely producing heat and light is called combustion.”

The Carbon content of bone charcoal is separated by treating the latter with hydrchloride acid, which dissolves the calcium phosphate. Carbon is then filtered out of the solution and in this form it is called bone black.

The heating-up of the earth’s atmosphere due to trapped infrared rays reflected from the earth's surface by atmospheric gases is called the greenhouse effect.

1. Acid rain forms when rainwater absorbs industrial gases like CO₂, SO₂, and nitrogen oxides, making it more acidic.
2. It harms soil and vegetation, corrodes buildings, damages monuments by reacting with calcium, and reduces visibility.
3. It also acidifies water bodies, endangering fish and aquatic life.
4. Soil pollution reduces soil fertility and nutrients.
5. Waste control is essential to protect soil health.