Answer: carbon dioxide.
- A oxygen gas
- B carbon dioxide
- C nitrogen gas
- D argon gas
Correct answer: B. carbon dioxide
Explanation: Carbon dioxide is the principal greenhouse gas released by burning fossil fuels.
Classical smog is a reducing mixture of SO₂ and fog, while photochemical smog is an oxidising mixture generated by UV-driven reactions of NOx and hydrocarbons.
Concept context
Understand how human activities alter the atmosphere, water, and soil. Covers air pollutants, smog types, ozone depletion, acid rain, greenhouse effect, water and soil pollution, and the principles of green chemistry.