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GATE 2022 ES – Question 43

Environmental Chemistry · Atmospheric Chemistry · 2 marks · Multiple select

Which statements are NOT correct for nighttime tropospheric chemistry?

  1. $NO_2+h\nu\to NO+O$
  2. Most NOx converts to NO
  3. $NO+O_3\to NO_2+O_2$
  4. Most NOx converts to NO₂

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Correct answer: (A) $NO_2+h\nu\to NO+O$; (B) Most NOx converts to NO

Explanation

Night removes the sunlight needed for ordinary NO₂ photolysis, so A does not describe the nighttime photochemical pathway. Ozone can oxidize NO to NO₂, favouring NO₂ rather than NO. Thus the incorrect statements are **A, B**; C and D describe the intended nighttime trend.

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