NPTEL Air Pollution and Control Week 10 Assignment Answers 2024
1. A cyclone has an inlet width of 20 cm and five effective turns (N = 5). The gas temperature is 350⁰K, and the inlet velocity is 10 m/s. The average particle density is 1.5 g/cm3. What is the cut diameter (particle size collected with 50% efficiency)? The viscosity of air at 350⁰K is 0.0748 kg/m-h.
- 6.94 µm
- 8.33 µm
- 12.14 µm
- 15.55 µm
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2. In a bag house filter, the incoming velocity of the gas is 800 m3/min. the filtering velocity is 4 m/min. Each bag is 20 cm wide and 3 m in length. If the spacing between each bag is 30 m and the wall is 30 cm, the number of bags required is________.
- 95
- 106
- 144
- 225
Answer :-
3. An electrostatic precipitator, in which the collection plate area is 100 m2, gas flow rate is 3 m3/s, and collection efficiency is 99.5%. The migration velocity is______(in m/s):
- 0.16
- 0.67
- 1.54
- 2.15
Answer :-
4. Single-stage electrostatic precipitator consisting of two sections formed by plates 5.0 m wide and 7.0 m high on 25 cm centers, handling a gas flow of 3 m3/s. Assume that the migration velocity is 12 cm/s. The collection efficiency of a horizontal flow is__________(in %).
- 98.55 %
- 98.25 %
- 99.63 %
- 99.25 %
Answer :-
5. Gravitational settling chamber under the following conditions:
I. Air: Horizontal velocity is 1 m/s
Temperature is 75⁰C
II. Particle: Specific gravity is 1.5
III. Chamber: Length is 10 m and Height is 2 m
IV. At 75⁰C viscosity of air is 2.1×10-5 kg/m-s
The minimum size of the particle is____________, that will be removed with 100 per cent efficiency.
- 65.28 µm
- 71.68 µm
- 83.55 µm
- 90.67 µm
Answer :-
6. Which of the following pollutants is not included in the revised National Ambient Air Quality Standard (NAAQS, 2009):
- Ozone
- Benzene
- Arsenic
- Cadmium
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7. What is the annual permissible limit for PM2.5 in ambient air as per WHO guidelines 2021?
- 5 µg/m³
- 10 µg/m³
- 25 µg/m³
- 50 µg/m³
Answer :-
8. What is the primary goal of the National Clean Air Programme (NCAP) in India?
- To completely eliminate PM emissions by 2025
- To achieve a 20–30% reduction in PM2.5 and PM10 levels by 2024
- To reduce vehicular emissions in all cities
- To promote urbanization in non-attainment areas
Answer :-
9. What is the focus of the Graded Response Action Plan (GRAP)?
- Managing waste in urban areas
- Reducing air pollution during severe episodes in Delhi NCR
- Expanding public transportation networks
- Implementing electric vehicle subsidies
Answer :-
10. Which Indian policy promotes the adoption of electric vehicles to reduce vehicular emissions?
- National Electric Mobility Mission Plan (NEMMP)
- Make in India Program
- National Renewable Energy Policy
- National Highway Development Project
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