What is the primary composition of clean air?

• 99% nitrogen and oxygen

• 99% carbon dioxide and argon

• 99% water vapor and ozone

• 99% hydrogen and helium

What is smog a mixture of?

• Smoke and fog

• Water vapor and ozone

• Nitrogen and helium

• Carbon dioxide and argon

The Clean Air Act was enacted in the United States in ____.

Point sources of air pollution involve a single source. An example of point-source air pollution is ____.

Which technology is used to convert car exhaust into less harmful gases?

• Catalytic converter

• Electric battery

• Hybrid engine

• Scrubber