Understanding Air Composition and Pollution

What is the approximate number of molecules in a single breath?

• 25 million

• 25 trillion

• 25 billion

• 25 sextillion

What percentage of Earth's atmosphere is composed of nitrogen?

• 21%

• 50%

• 78%

• 0.93%

Which gas accounts for 21% of Earth's atmosphere?

• Oxygen

• Carbon Dioxide

• Argon

• Nitrogen

What is the main source of argon in the atmosphere?

• Volcanic activity

• Radioactive decay of potassium

• Combustion of fossil fuels

• Photosynthesis

What percentage of air is composed of trace gases and particles?

• 10%

• 5%

• 1%

• 0.07%

What are primary pollutants?

• Compounds formed by natural processes

• Toxic compounds directly emitted from sources

• Gases that make up the majority of the atmosphere

• Particles that are harmless to humans

What is a common source of polycyclic aromatic hydrocarbons?

• Ocean evaporation

• Burning wood or dung

• Photosynthesis

• Volcanic eruptions

What is a secondary pollutant formed from sulfur oxides?

• Methane

• Carbon monoxide

• Sulfates

• Ozone

What is a major contributor to photochemical smog?

• Sulfur oxides

• Argon

• Water vapor

• Nitrogen oxides and hydrocarbons

What is one measure taken to reduce vehicle emissions?

• Using leaded gasoline

• Reducing oxygen levels

• Installing catalytic converters

• Increasing coal usage