Which of the following statements are correct?
(A) Global warming is a gradual increase in the average temperature of the earth’s lower atmosphere.
(B) Ozone depletion refers to reductions in the amount of ozone in the stratosphere.
(C) Global warming is caused mainly by high levels of chlorine and bromine compounds in the stratosphere.
(D) Methane gas released in animal waste is a cause of ozone depletion.
(E) Bromofluorocarbons used in fire extinguishers are a source of ozone-depleting compounds.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (B) and (E) only
Global warming and ozone depletion are two different problems with different causes. Greenhouse gases such as carbon dioxide and methane cause global warming. Chlorine and bromine compounds from CFCs and halons cause ozone depletion.
(A) Global warming is a gradual increase in the average temperature of the earth’s lower atmosphere. — Correct. This is the meaning of global warming.
(B) Ozone depletion refers to reductions in the amount of ozone in the stratosphere. — Correct. This is the meaning of ozone depletion.
(C) Global warming is caused mainly by high levels of chlorine and bromine compounds in the stratosphere. — Incorrect. These compounds cause ozone depletion. Global warming comes from more greenhouse gases.
(D) Methane gas released in animal waste is a cause of ozone depletion. — Incorrect. Methane is a factor in global warming, not in ozone depletion.
(E) Bromofluorocarbons used in fire extinguishers are a source of ozone-depleting compounds. — Correct. Halons are one of the origins of the bromine compounds that deplete ozone.
NCERT (2026-27): “Box 7.1: Global Warming Global warming is a gradual increase in the average temperature of the earth’s lower atmosphere as a result of the increase in greenhouse gases since the Industrial Revolution. … 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. …” “Box 7.2: Ozone Depletion Ozone depletion refers to the phenomenon of reductions in the amount of ozone in the stratosphere. 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. …” |