Air Pollution and Control Week 5 NPTEL Assignment Answers 2025

NPTEL Air Pollution and Control Week 5 Assignment Answers 2024

1. What is the primary cause of exhaust emissions from vehicles?

• Brake wear
• Road resuspension
• Incomplete combustion in the engine chamber
• Evaporation of gasoline

Answer: c
Explanation: Exhaust emissions primarily result from the incomplete combustion of fuel in the engine chamber, which leads to pollutants like CO, NOx, and HC being released into the atmosphere.

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2. What pollutants are associated with non-exhaust emissions from vehicles?

• PM10, PM2.5, and heavy metals
• Carbon monoxide (CO)
• Hydrocarbons (HC)
• Nitrogen oxides (NOx)

Answer: a
Explanation: Non-exhaust emissions arise from brake wear, tire wear, and road dust resuspension, which release particulate matter (PM10, PM2.5) and heavy metals into the air.

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3. Which of the following air pollutants is NOT considered in the VAPI (Vehicular Air Pollution Inventory) model?

• CO
• CO2
• PM
• O3

Answer: d
Explanation: The VAPI model focuses on pollutants directly emitted from vehicles like CO, CO2, and PM. Ozone (O3) is a secondary pollutant formed in the atmosphere and is not directly modeled in VAPI.

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4. Emissions of which of the following air pollutants is NOT estimated by the GAINS model?

• Heavy metals
• PM
• VOC
• NH3

Answer: a
Explanation: The GAINS model estimates emissions of major pollutants including PM, VOCs, NOx, SO2, and NH3, but it does not include heavy metals in its standard inventory.

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5. What modes of operation are available for the GAINS (Greenhouse Gas and Air Pollution Interactions and Synergies) model?

• Only in “optimization” mode
• Only in “scenario analysis” mode
• Only in “simulation” mode
• In both “scenario analysis” and “optimization” modes

Answer: d
Explanation: The GAINS model supports both scenario analysis and optimization, allowing policymakers to evaluate strategies for reducing air pollution and greenhouse gas emissions.

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6. There are emissions of various pollutants and GHGs from agricultural activities. Which of the following GHGs is released by livestock’s enteric fermentation and rice cultivation?

• N2O
• CO2
• CH4
• O3

Answer: c
Explanation: Methane (CH4) is released during enteric fermentation in livestock and anaerobic decomposition in flooded rice fields.

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7. How do NH3 emissions from agricultural activities interact in the atmosphere, producing secondary inorganic aerosols?

• React with CO2
• React with CH4
• React with SO2 and NOx
• React with O3

Answer: c
Explanation: Ammonia (NH3) reacts with sulfur dioxide (SO2) and nitrogen oxides (NOx) in the atmosphere to form secondary inorganic aerosols, such as ammonium sulfate and ammonium nitrate.

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8. Which of the following is considered as a fuel combustion activity in the commercial sector?

• Domestic cooking
• Boiler operation
• Fireplace use
• Rural heating

Answer: b
Explanation: Boiler operation is a typical fuel combustion activity in the commercial sector, used for generating heat or steam.

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9. Aerosol Optical Depth expresses the quantity of light removed from a beam by ___ by aerosols during its path through the atmosphere.

• Dispersion
• Diffusion
• Scattering
• Adsorption

Answer: c
Explanation: Aerosol Optical Depth (AOD) measures light scattering and absorption by aerosols. Among the options, scattering is the main mechanism considered.

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10. What does Aerosol Optical Depth (AOD) correlate in satellite-based air quality monitoring?

• Atmospheric pressure
• Atmospheric temperature
• Particulate concentrations
• Wind velocity

Answer: c
Explanation: AOD correlates strongly with particulate matter concentrations in the atmosphere, helping monitor air pollution using satellite remote sensing.