Question

Given below are two statements : Statement I : An allotrope of oxygen is an important intermediate in the formation of reducing smog. Statement II : Gases such as oxides of nitrogen and sulphur present in troposphere contribute to the formation of photochemical smog. In the light of the above statements, choose the correct answer from the options given below :

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is true but Statement II is false
• D. Statement I is false but Statement II is true

Hint:

Remember: {Classical Smog} = $SO_2$ + Smoke + Fog (occurs in cool humid climates). {Photochemical Smog} = $NO_2$ + $O_3$ + PAN (occurs in warm, dry, and sunny climates).

Answer 1

The Correct Option is B

Step 1: Reducing smog (Classical smog) is a mixture of smoke, fog, and sulphur dioxide ($SO_2$). It does not involve Ozone ($O_3$, an allotrope of oxygen) as an intermediate. Ozone is a key component of photochemical smog. Thus, Statement I is false.
Step 2: Photochemical smog is formed by the action of sunlight on unsaturated hydrocarbons and nitrogen oxides. While $NO_x$ contributes to it, oxides of sulphur ($SO_2$) are primarily responsible for reducing smog, not photochemical smog. Thus, Statement II is false.