GATE CE 2021 Set 2 — Question 42
Go beyond PYQs with Success TrackerAI-powered personalised practice and doubt support. Unlimited practice on eligible plans; AI usage limits apply.MCQ+2 / -0.67MediumGaussian Plume ModelAir PollutionEnvironmental Engineering
Environmental Engineering → Air Pollution → Gaussian Plume Model
Last updated
Question
Read the statements given below.
(i) Value of the wind profile exponent for the 'very unstable' atmosphere is smaller than the wind profile exponent for the 'neutral' atmosphere.
(ii) Downwind concentration of air pollutants due to an elevated point source will be inversely proportional to the wind speed.
(iii) Value of the wind profile exponent for the 'neutral' atmosphere is smaller than the wind profile exponent for the 'very unstable' atmosphere.
(iv) Downwind concentration of air pollutants due to an elevated point source will be directly proportional to the wind speed.
Select the correct option.
(i) Value of the wind profile exponent for the 'very unstable' atmosphere is smaller than the wind profile exponent for the 'neutral' atmosphere.
(ii) Downwind concentration of air pollutants due to an elevated point source will be inversely proportional to the wind speed.
(iii) Value of the wind profile exponent for the 'neutral' atmosphere is smaller than the wind profile exponent for the 'very unstable' atmosphere.
(iv) Downwind concentration of air pollutants due to an elevated point source will be directly proportional to the wind speed.
Select the correct option.
Correct answer
(D) (iii) is False and (iv) is False
Solution
Let's analyze each statement:(i) Value of the wind profile exponent for the 'very unstable' atmosphere is smaller than the wind profile exponent for the 'neutral' atmosphere.
- The wind profile exponent (p) in the power law is related to atmospheric stability. For unstable conditions, there is more vertical mixing, leading to a more uniform wind profile with height, hence a smaller exponent. For neutral conditions, the exponent is higher than for unstable conditions. Therefore, this statement is True.
- According to the Gaussian plume model, the concentration of pollutants () is inversely proportional to the wind speed (). A higher wind speed means the plume is stretched more horizontally, leading to lower concentrations. So, . Therefore, this statement is True.
- This is the inverse of statement (i). As explained above, the wind profile exponent for neutral atmosphere is larger than for very unstable atmosphere. Therefore, this statement is False.
- This is the inverse of statement (ii). As explained above, the concentration is inversely proportional to the wind speed. Therefore, this statement is False.
- (A) (i) is False and (iii) is True: Incorrect, (i) is True and (iii) is False.
- (B) (i) is True and (iv) is True: Incorrect, (iv) is False.
- (C) (ii) is False and (iii) is False: Incorrect, (ii) is True.
- (D) (iii) is False and (iv) is False: Correct, both (iii) and (iv) are False.
Continue learning with Success Tracker
A step still unclear? Work through it with support
Use Success Tracker to ask about the reasoning, then try another GATE CE question to check your understanding.
AI-powered practice· Unlimited practice on eligible plans
- PYQs with solutions
- Attempt available previous-year questions, then compare your reasoning with the worked solution. Coverage varies by stream.
- Practice that adapts
- Choose a topic, work on weaker areas and bookmark questions to revisit. Your attempts feed your progress tracking.
- AI doubt support
- Ask follow-up questions about a step or concept while practising, instead of stopping at the final answer.
Unlimited practice is available on eligible plans. Free practice and AI usage have limits; check the current plan allowances before choosing.
This page stays readable without an account. AI responses can be wrong; check them against the solution and source material.
More questions on Air Pollution
2026 Set 1 Q21A rapid sand filter bed of depth m has % porosity during service cycle. It is…2026 Set 1 Q22The settling velocity of inorganic particles in the sedimentation tank of a water treatment plant…2026 Set 1 Q25Which of the following components is/are NOT removed in the secondary treatment of sewage?2026 Set 2 Q27Column I presents common air pollutants, and column II presents treatment technologies commonly…2026 Set 2 Q28One-third of the solid matter in a sludge containing water is composed of fixed mineral…