Answer: Dobson units.
- A Dobson units
- B decibels
- C parts per million
- D micrograms
Correct answer: A. Dobson units
Explanation: Ozone thickness is expressed in Dobson units (DU); decibels measure sound, while parts per million and micrograms are general concentration units.
Sunlight passes through the atmosphere and warms the surface; the surface re-radiates this energy as infrared heat, which greenhouse gases (CO₂, CH₄, water vapour) absorb and trap - a naturally beneficial process that intensifies into global warming as gas concentrations rise from human activity.
Concept context
Pollution, global warming, ozone depletion, deforestation, and sustainability. Important for NEET and general awareness.