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Difficulty: Very hardEnvironmental Pollution: Types, Causes and Control Measures

Consider the following statements regarding industrial pollution control technologies and atmospheric chemical phenomena:

1. Catalytic converters fitted in automobiles utilize platinum-palladium and rhodium catalysts to reduce toxic emissions by converting unburnt hydrocarbons into CO2CO_2 and H2OH_2O, carbon monoxide into CO2CO_2, and nitric oxide into N2N_2 gas.
2. Electrostatic Precipitators (ESPs) deployed in thermal power plants remove over 99% of particulate matter by generating an electric corona that imparts a negative charge to dust particles, which are then collected on grounded plates.
3. Photochemical smog is classified as a reducing smog because it primarily consists of high concentrations of sulfur dioxide (SO2SO_2) and particulate matter formed under cold, humid weather conditions.

Which of the statements given above are correct?

  1. 1 and 2 onlyAnswer
  2. B
    2 and 3 only
  3. C
    1 and 3 only
  4. D
    1, 2 and 3

Answer

The statements 1 and 2 only are correct.
Statements 1 and 2 accurately present the operating chemistry and physics of primary air pollution abatement systems (catalytic converters and electrostatic precipitators). Statement 3 incorrectly characterizes Photochemical smog as a reducing mixture; Photochemical smog is strongly oxidizing due to high levels of ground-level ozone and PAN generated via photochemical reactions of nitrogen oxides and hydrocarbons in warm, sunny environments.

Step-by-Step Solution

1
Analyze Statement 1 regarding catalytic converters
Statement 1 is correct. Catalytic converters use noble metals (platinum, palladium, rhodium) to oxidize hydrocarbons to CO2CO_2 and H2OH_2O, oxidize COCO to CO2CO_2, and reduce NOxNO_x to inert nitrogen gas (N2N_2).
Verifying chemical transformations induced by automotive emission abatement technologies.
2
Analyze Statement 2 regarding Electrostatic Precipitators
Statement 2 is correct. High voltage electrode wires produce a corona discharge releasing electrons, which attach to dust particles to give them a net negative charge so they can be attracted to positively charged/grounded collecting plates.
Evaluating particulate control technology efficiency and electro-physical operating principles in power plants.
3
Analyze Statement 3 regarding smog types and chemical characteristics
Statement 3 is incorrect. Photochemical smog occurs in warm, sunny climates and is an oxidizing mixture containing secondary pollutants like O3O_3, PAN, and aldehydes. Classical smog is reducing smog, dominated by SO2SO_2 and coal smoke in cold, humid climates.
Distinguishing between primary/secondary pollutant dynamics and atmospheric smog oxidation states.

Key Concept

Air Pollution Abatement Technologies and Atmospheric Photochemical Reactions
Estimated Time:1m 30s
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Topics

Environmental Pollution: Types, Causes and Control Measures