NCEES FE Environmental · USA · National Council of Examiners for Engineering and Surveying
Original practice questions written to the published syllabus · not past papersAir pollutants, their health and crop effects, standards and indices, dispersion, and control equipment, plus noise. Agricultural sources (residue burning, ammonia, dust, odour) are covered here alongside the industrial ones GATE ES examines.
In the exams: GATE ES Section 6 (whole section, numerical); ICAR AICE subject 71 Unit 3; UGC NET Unit 6; state pollution control board recruitment
NCEES FE Environmental
Air quality engineering calculations: dispersion, control device efficiency, combustion and emission estimates, and noise.
How our questions for NCEES FE Environmental spread across the units of Air & Noise Pollution: Monitoring & Control. Difficulty: 6 easy, 24 medium, 13 hard.
| Particulate control: settling chambers, cyclones, wet scrubbers, fabric filters, ESP | 8 | |
| Gaussian plume dispersion modelling | 7 | |
| Gaseous control: absorption, adsorption, condensation, combustion | 6 | |
| Noise: sources, effects, standards, measurement and control | 6 | |
| Control of SOx, NOx, CO and hydrocarbons; vehicle emissions | 5 | |
| Meteorology and dispersion: stability, mixing height, wind rose | 4 | |
| Emission inventories for point, line and area sources | 3 | |
| Indoor air pollution | 2 | |
| Criteria pollutants, ambient and emission standards | 1 | |
| Air quality indices and visibility | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
A room of 200 m³ receives 1000 m³ of outdoor air per hour. How many air changes per hour (ACH) is this?
A. 5
ACH = 1000/200 = 5. 0.2 inverts the ratio; 200 is the volume; 1200 adds.
Further reading: See the manual sources: de Nevers; Cooper & Alley; CPCB NAAQS and AQI; WHO 2021 AQG; Noise Rules 2000
In a simple box model, C = qL/(uH), what happens to the urban concentration if the mixing height halves?
B. It doubles
C is inversely proportional to mixing height H.
Further reading: See the manual sources: de Nevers; Cooper & Alley; CPCB NAAQS and AQI; WHO 2021 AQG; Noise Rules 2000
What is 'breakthrough' in a fixed-bed adsorber?
A. When outlet concentration starts to rise
As the mass transfer zone reaches the outlet, pollutant appears in the effluent and the bed must be regenerated.
Further reading: See the manual sources: de Nevers; Cooper & Alley; CPCB NAAQS and AQI; WHO 2021 AQG; Noise Rules 2000
Condensation is most suitable for VOC streams that are
D. concentrated, with high boiling points
Cooling condenses VOCs efficiently only when concentrations and boiling points are high.
Further reading: See the manual sources: de Nevers; Cooper & Alley; CPCB NAAQS and AQI; WHO 2021 AQG; Noise Rules 2000
In wet limestone flue gas desulphurisation, the main by-product is
B. gypsum, calcium sulphate
SO2 reacts with limestone and is oxidised to gypsum, usable in wallboard and cement.
Further reading: See the manual sources: de Nevers; Cooper & Alley; CPCB NAAQS and AQI; WHO 2021 AQG; Noise Rules 2000
Selective catalytic reduction of NOx uses which reagent?
D. Ammonia or urea over a catalyst
SCR injects NH3 or urea upstream of a catalyst at about 300–400 °C, reducing NOx to N2.
Further reading: See the manual sources: de Nevers; Cooper & Alley; CPCB NAAQS and AQI; WHO 2021 AQG; Noise Rules 2000
Thermal NOx forms mainly
A. from air N2 and O2 in very hot flames
Thermal NOx forms above roughly 1300 °C; fuel NOx comes from fuel-bound nitrogen.
Further reading: See the manual sources: de Nevers; Cooper & Alley; CPCB NAAQS and AQI; WHO 2021 AQG; Noise Rules 2000
A plant burns 1000 tonnes of coal per day containing 0.5 per cent sulphur. Assuming all sulphur is emitted as SO2, how much SO2 is emitted per day?
A. 10 tonnes
S = 1000 × 0.005 = 5 t; SO2 = 2 × 5 = 10 t (64/32). 5 forgets the factor 2; 20 doubles twice; 0.5 slips.
Further reading: See the manual sources: de Nevers; Cooper & Alley; CPCB NAAQS and AQI; WHO 2021 AQG; Noise Rules 2000
With a 3 dB exchange rate and a limit of 85 dB(A) for 8 hours, how long may a worker be exposed to 91 dB(A)?
D. 2 hours
Each 3 dB halves the time: 88 dB → 4 h, 91 dB → 2 h.
Further reading: See the manual sources: de Nevers; Cooper & Alley; CPCB NAAQS and AQI; WHO 2021 AQG; Noise Rules 2000
Increasing sound intensity tenfold raises the sound level by
B. 10 dB
L = 10 log(I/I0); ×10 intensity = +10 dB; doubling = +3 dB.
Further reading: See the manual sources: de Nevers; Cooper & Alley; CPCB NAAQS and AQI; WHO 2021 AQG; Noise Rules 2000
Ten here, 43 in the app. The Laisha app has every practice question we have written to NCEES FE Environmental in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
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