Which one of the following is the odd one out with respect to the origins of the compounds that cause ozone depletion?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Methane gas released in animal waste
Ozone depletion is caused by chlorine and bromine compounds in the stratosphere. These come from CFCs and halons, the first three items.
Methane gas released in animal waste is a factor that may be contributing to global warming. It is not a source of ozone-depleting compounds, so it is the odd one out.
NCERT (2026-27): “Box 7.2: Ozone Depletion … The problem of ozone depletion is caused by high levels of chlorine and bromine compounds in the stratosphere. The origins of these compounds are chlorofluorocarbons (CFC), used as cooling substances in air-conditioners and refrigerators, or as aerosol propellants, and bromofluorocarbons (halons), used in fire extinguishers. …” “Box 7.1: Global Warming … Among factors that may be contributing to global warming are the burning of coal and petroleum products (sources of carbon dioxide, methane, nitrous oxide, ozone); deforestation, which increases the amount of carbon dioxide in the atmosphere; methane gas released in animal waste; and increased cattle production, which contributes to deforestation, methane production, and use of fossil fuels. …” |