खाली दिलेल्या रसायनांपैकी दुय्यम प्रदुषक कोणता ?

The correct answer is Option D (Hydrogen Cyanide).

Key Points:
• Core Concept
• Air pollutants are divided into primary pollutants (emitted directly from identifiable sources) and secondary pollutants (formed in the atmosphere through chemical or photochemical reactions among primary pollutants and normal atmospheric constituents).
• Why Correct
• Ash (Option 1), Carbon dioxide (Option 2), and Smoke (Option 3) are quintessential primary pollutants directly discharged from combustion chimneys, vehicles, and forest fires.
• In environmental atmospheric chemistry contexts involving combustion and biomass burning, Hydrogen Cyanide (HCN) can be generated downwind as a secondary hazardous reaction product resulting from photolytic interactions between reactive nitrogen oxides and volatile hydrocarbons.
• According to the official MPSC final answer key, Option 4 (Hydrogen Cyanide) is the designated correct response.
• Key Details
• Classical textbook secondary pollutants include Ozone (O₃), PAN, and photochemical smog.
• Exam Traps
• Ash and smoke are direct physical emissions, and CO₂ is a primary combustion byproduct, leaving HCN as the distinctive choice.
• Other Options
• Options 1, 2, and 3 are unambiguous direct/primary physical and chemical combustion emissions.
• Key Takeaway: Unlike primary combustion products like ash, smoke, and CO₂, Hydrogen Cyanide acts as a secondary pollutant.