INSIGHT UPSC QUIZ

Science & Technology General Science
Q.

 Consider the following statements about ‘Photochemical Smog’: 

1. It is a phenomenon of cool humid climate. 

2. It occurs when sunlight acts on unburnt hydrocarbons and nitrogen oxides.

3. Ozone in photochemical smog is responsible for the haze. 

Which of the statements given above is/are correct?

Explanation:

ANSWER: (B) 

  • The word smog is derived from smoke and fog. Photochemical smog occurs in warm, dry and sunny climate. (Thus, Statement 1 is not correct) 
  • The main components of the photochemical smog result from the action of sunlight on unsaturated hydrocarbons (unburnt fuels) and nitrogen oxides produced by automobiles and factories. (Thus, Statement 2 is correct) 
  • Nitrogen dioxide (NO2) is a brown gas and at sufficiently high levels can contribute to haze. (Thus, Statement 3 is not correct) 
  • The common components of photochemical smog are ozone, nitric oxide, acrolein, formaldehyde and peroxyacetyl nitrate (PAN). Photochemical smog causes serious health problems. Both ozone and PAN act as powerful eye irritants. Photochemical smog leads to cracking of rubber and extensive damage to plant life. It also causes corrosion of metals, stones, building materials, rubber and painted surfaces. 

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