Summary
Air is a mixture of gases, primarily composed of approximately 78% nitrogen and 21% oxygen, with the remainder being noble gases and carbon dioxide. Common air pollutants include carbon monoxide, sulfur dioxide, oxides of nitrogen, carbon dioxide, and methane, which have various adverse effects on health and the environment.
- Carbon Monoxide — a poisonous gas that reduces the oxygen-carrying capacity of blood.
Example: Emitted from incomplete combustion of carbon-containing substances. - Sulfur Dioxide — a gas that contributes to acid rain, harming plants and aquatic life.
Example: Produced from burning fossil fuels containing sulfur. - Oxides of Nitrogen — gases that form smog and acid rain, causing respiratory issues.
Example: Generated in car engines. - Carbon Dioxide — a greenhouse gas contributing to global warming.
Example: Formed from complete combustion of carbon-containing fuels. - Methane — a potent greenhouse gas contributing to global warming.
Example: Released from decomposition of organic matter and animal digestion.
Exam Tips
Key Definitions to Remember
- Composition of clean air
- Sources and effects of common air pollutants
- Photosynthesis process and equation
Common Confusions
- Difference between complete and incomplete combustion
- Effects of greenhouse gases vs. pollutants causing acid rain
Typical Exam Questions
- What is the composition of clean air? Approximately 78% nitrogen, 21% oxygen, and trace amounts of other gases.
- How do catalytic converters reduce pollution? They convert harmful gases into less harmful substances using catalysts.
- What is the role of photosynthesis in the environment? It converts carbon dioxide and water into glucose and oxygen, reducing CO2 levels.
What Examiners Usually Test
- Understanding of air composition and pollutants
- Ability to explain the effects of pollutants on health and the environment
- Knowledge of methods to reduce emissions and their effectiveness