Question

Identify the sets which contain greenhouse gases only:  I. $CO_{2}$, $SO_{3}$, $N_{2}$  II. $CO_{2}$, $CH_{4}$, $O_{3}$  III. $O_{2}$, $NO_{2}$, $SO_{2}$  IV. $O_{3}$, CFCs, $N_{2}O$  The correct answer is:

• A. I, II only
• B. II, III only
• C. II, IV only
• D. I, IV only

Hint:

Elementary gases like $N_{2}$ and $O_{2}$ never contribute to the greenhouse effect because they lack a changing dipole moment when vibrating.

Answer 1

The Correct Option is C

Step 1: Concept
Greenhouse gases (GHGs) are atmospheric gases capable of trapping infrared radiation, thereby retaining heat within the atmosphere. Major examples include carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbons.

Step 2: Meaning
To fit the "greenhouse gases only" criteria, every single chemical species present within that designated set must function as a greenhouse active component.

Step 3: Analysis
Let us look at each group: Set I: Contains $N_{2}$ and $SO_{3}$, which are not categorized as traditional greenhouse gases. Set II: Carbon dioxide ($CO_{2}$), methane ($CH_{4}$), and ozone ($O_{3}$) are all prominent greenhouse gases. Set III: Oxygen ($O_{2}$) and sulfur dioxide ($SO_{2}$) are not greenhouse gases. Set IV: Ozone ($O_{3}$), Chlorofluorocarbons (CFCs), and nitrous oxide ($N_{2}O$) are all greenhouse gases.

Step 4: Conclusion
Therefore, only sets II and IV contain greenhouse components exclusively.

Final Answer: (C)