⚡ Quick Revision: Air at a Glance
- Air is a mixture, not a pure substance.
- Main gases in air are nitrogen and oxygen.
- Air also contains carbon dioxide, water vapour, dust and noble gases.
Makeup: 2 Oxygen atoms joined together.
Makeup: 2 Nitrogen atoms joined together.
Makeup: 1 Carbon atom + 2 Oxygen atoms.
Fuel + Oxygen → Heat + Light + New Substances
Observation: Oxygen supports burning.
Air is a mixture of gases vs Oxygen is only one gas present in air.
Do not write that air is oxygen. Oxygen is only a part of air.
N-O-C-W-D
Nitrogen, Oxygen, Carbon dioxide, Water vapour, Dust are present in air.
| Component of Air | Symbol / Formula | Quick Use / Recall |
|---|---|---|
| Nitrogen | N₂ | Most abundant gas in air 🔥 |
| Oxygen | O₂ | Needed for breathing and burning |
| Carbon Dioxide | CO₂ | Used by plants in photosynthesis |
| Water Vapour | H₂O | Helps in cloud formation |
- Air is a mixture of gases.
- Nitrogen is the major gas in air.
- Oxygen supports breathing and burning.
- Carbon dioxide is used by plants.
- Atmosphere is the layer of air around Earth.
⚡ Quick Revision: Composition and Importance of Air
- Air contains about 78% nitrogen and 21% oxygen.
- Oxygen supports respiration and combustion.
- Carbon dioxide is needed for photosynthesis.
Makeup: 2 Oxygen atoms joined together.
Makeup: 2 Nitrogen atoms joined together.
Makeup: 1 Carbon atom + 2 Oxygen atoms.
Food + Oxygen → Energy + Carbon Dioxide + Water
Observation: Living things use oxygen to release energy from food.
Carbon Dioxide + Water + Sunlight → Food + Oxygen
Observation: Green plants use carbon dioxide and release oxygen.
Respiration uses oxygen and releases carbon dioxide vs Photosynthesis uses carbon dioxide and releases oxygen.
Do not write oxygen as the major gas in air. Nitrogen is the major gas in air.
78-N, 21-O
Remember: 78% Nitrogen and 21% Oxygen are the two main parts of air.
| Gas | Approximate Amount | Importance |
|---|---|---|
| Nitrogen | About 78% | Major gas in air 🔥 |
| Oxygen | About 21% | Breathing and burning |
| Carbon Dioxide | Very small amount | Photosynthesis |
| Water Vapour | Variable | Cloud and rain formation |
- Nitrogen is about 78% of air.
- Oxygen is about 21% of air.
- Oxygen is needed for respiration.
- Carbon dioxide is needed for photosynthesis.
- Water vapour helps in cloud formation.
⚡ Quick Revision: Atmosphere and Layers Recall
- The atmosphere protects life on Earth.
- Weather changes mainly occur in the troposphere.
- The ozone layer protects us from harmful ultraviolet rays.
Makeup: 3 Oxygen atoms joined together.
Makeup: 2 Oxygen atoms joined together.
Ozone Layer + Harmful UV Rays → Protection for Earth
Observation: The ozone layer reduces harmful rays reaching Earth.
Air is the mixture of gases vs Atmosphere is the layer of air around Earth.
Do not write that ozone is O₂. Oxygen gas is O₂, but ozone is O₃.
T-S-O
Troposphere has weather, Stratosphere has Ozone.
| Layer / Term | Quick Meaning | Exam Recall |
|---|---|---|
| Atmosphere | Air blanket around Earth | Protects life |
| Troposphere | Lowest layer | Weather occurs here 🔥 |
| Stratosphere | Layer above troposphere | Contains ozone layer |
| Ozone Layer | Protective layer | Absorbs UV rays |
- Atmosphere is the blanket of air around Earth.
- Troposphere is the lowest layer.
- Weather occurs in the troposphere.
- Stratosphere contains the ozone layer.
- Ozone is O₃ and protects Earth from harmful UV rays.
⚡ Quick Revision: Air Pollution and Prevention
- Smoke, dust and harmful gases are common air pollutants.
- Vehicles, factories and burning waste cause air pollution.
- Air pollution can cause breathing problems and harm plants and animals.
Makeup: 1 Carbon atom + 2 Oxygen atoms.
Makeup: Reducing smoke and planting trees help improve air quality.
Fuel + Oxygen → Carbon Dioxide + Water Vapour + Heat
Observation: Burning fuels may release smoke and harmful gases.
Clean air has fewer harmful substances vs Polluted air contains smoke, dust and harmful gases.
Do not write that only factories cause air pollution. Vehicles, burning waste, firecrackers and dust also pollute air.
S-D-G
Smoke, Dust and harmful Gases are common air pollutants.
| Pollutant | Source | Effect |
|---|---|---|
| Smoke | Vehicles, factories, burning waste | Breathing problems 🔥 |
| Dust | Roads, construction, wind | Eye and nose irritation |
| Harmful Gases | Factories and fuel burning | Pollutes air and harms health |
| Firecracker Smoke | Firecrackers | Air and noise pollution |
- Air pollution means harmful substances in air.
- Smoke, dust and harmful gases are pollutants.
- Vehicles and factories can pollute air.
- Air pollution can cause breathing problems.
- Planting trees and reducing smoke help keep air clean.
⚡ Quick Revision: Final Exam Recall Sheet
- 🔥 Air is a mixture of gases, not a compound.
- 🔥 Nitrogen is the major gas in air, about 78%.
- 🔥 Oxygen supports breathing and burning.
Makeup: 2 Nitrogen atoms joined together.
Makeup: 2 Oxygen atoms joined together.
Makeup: 1 Carbon atom + 2 Oxygen atoms.
Makeup: 3 Oxygen atoms joined together.
Food + Oxygen → Energy + Carbon Dioxide + Water
Observation: Living things use oxygen to release energy.
Carbon Dioxide + Water + Sunlight → Food + Oxygen
Observation: Green plants use carbon dioxide and release oxygen.
Fuel + Oxygen → Carbon Dioxide + Water Vapour + Heat
Observation: Burning may produce smoke and harmful gases.
Respiration uses oxygen and releases carbon dioxide vs Photosynthesis uses carbon dioxide and releases oxygen.
Do not write oxygen as the major gas in air. Nitrogen is the major gas in air.
78-N, 21-O, O₃-SAFE
78% Nitrogen, 21% Oxygen, and O₃ ozone keeps Earth safer from UV rays.
| Gas / Term | Formula / Meaning | Exam Recall |
|---|---|---|
| Nitrogen | N₂ | Major gas in air, about 78% 🔥 |
| Oxygen | O₂ | Breathing and burning |
| Carbon Dioxide | CO₂ | Used in photosynthesis |
| Ozone | O₃ | Absorbs harmful UV rays |
| Concept | Quick Meaning | Do Not Confuse |
|---|---|---|
| Air | Mixture of gases | Not only oxygen |
| Atmosphere | Air blanket around Earth | Not a single gas |
| Troposphere | Lowest layer | Weather occurs here 🔥 |
| Air Pollution | Harmful substances in air | Not caused only by factories |
Air → Mixture of Gases → Atmosphere → Protects Earth → Pollution Must Be Prevented
- Air is a mixture of gases.
- Nitrogen is the major gas in air.
- Oxygen is needed for respiration and burning.
- Atmosphere protects life on Earth.
- Air pollution is caused by smoke, dust and harmful gases.