Question
Which equation correctly represents the formation of ozone in the upper atmosphere?
This question was previously asked in
SSC Selection Post 2025 Graduate Level Question Paper (29-Aug-2025) (Shift 1)
The correct answer is
O2 + UV → O + O; O + O2 → O3
In the stratosphere, high-energy ultraviolet (UV) radiation splits an oxygen molecule into two free oxygen atoms: O2 + UV → O + O.
Each free oxygen atom then combines with another oxygen molecule to form ozone: O + O2 → O3. This two-step process (the Chapman mechanism) builds the ozone layer.
Splitting CO2 does not produce ozone; heat alone does not drive this photolysis; and O + O → O2 only re-forms ordinary oxygen, not ozone.
Hence, the answer is: O2 + UV → O + O; O + O2 → O3.
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Important Questions from Ozone Layer Depletion
- Which of the following is a catalytically inactive (or reservoir) molecule containing chlorine in stratosphere?
- Choose the correct statement(s)
A. O$_3$ in stratosphere is not completely effective in shielding us from UV-B
B. UV-A is biologically least harmful.
C. Chapman mechanism deals with only O$_3$ formation in stratosphere.
D. Sunscreen lotions either reflect or absorb or scatter UV-B and UV-A
E. UV-B helps in dissociation of O$_3$ molecule in stratosphere.
Choose the correct answer from the options given below. Ozone layer depletion is a major phenomenon in :
- With regard to ozone depletion over Antarctica, select the false statement :
- Atmospheric life times of CFCs is typically in the range :
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