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ICSE Class 9 Chemistry Question 27 of 31

Atmospheric Pollution — Question 14

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14
Question

Question 2(vi)

Assertion (A): UV radiations break ozone into O2 and O.

Reason (R): Ozone hole is responsible for global warming and climate change.

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not the correct explanation of A.
  3. A is true but R is false.
  4. A is false but R is true.
Answer

A is true but R is false.

Explanation— The Ozone layer is formed by the photolysis, it again absorbs UV radiation of comparatively longer wavelengths, breaking down again into oxygen molecule and oxygen atoms. Hence, the assertion (A) is true.

O3 ⟶ O2 + O

The ozone hole affects UV radiation reaching Earth's surface, leading to health and ecological issues. However, global warming and climate change are primarily caused by the greenhouse effect, driven by gases like CO2, CH4, and N2O — not by the ozone hole. Hence, the reason (R) is false.