Environmental Science and Engineering
GATE ES format:nat PYQs
Build your understanding with focused practice from past exam papers.
How to practice format:nat
Attempt a question, record the concept and assumptions, then check the available answer. Rework mistakes after revising the relevant concepts. Topic tags can overlap; review the question context.
Questions 1–10 of 122. Imported answers require independent review unless marked reviewed.
Question 34
Open questionESNAT1 markNeeds review
A 6-hour rainfall of 6 cm at a station was found to have a return period of 40 years. The probability that a 6-hour rainfall of this or larger magnitude will occur at least once in 20 successive years at that station is ______ (rounded off to three decimal places).
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Water is flowing at the rate of 15 m
/s through a rectangular channel of 5 m width. If the acceleration due to gravity (g) is 9.81 m/s
, the critical velocity for the flow is ______m/s (rounded off to three decimal places).Log in to check the answer
You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 47
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The sound level measured at various locations in an urban area is given in the table. The average sound level for that area is ______ dBA (rounded off to two decimal places).
Location | A | B | C | D |
|---|---|---|---|---|
Sound level (dBA) | 40 | 55 | 65 | 75 |
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Standard deviation for the particulate matter (PM) concentrations listed in the table is ______ μg/m³ (rounded off to one decimal place).
Location No. | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|
PM concentration (μg/m³) | 45 | 40 | 55 | 65 | 60 | 35 | 50 |
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 49
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The mixing ratio of CO₂ at a pressure of 1 atm and at 300K is reported as 340 ppmv. Considering ideal gas conditions, the equivalent concentration of CO₂ in air is ______ mg/m³ (rounded off to two decimal places).
The molecular weight of CO₂ = 44 g/mol
Universal gas constant = 8.314 J/mol-K
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Reaction A → B follows first-order element kinetics and the reaction rate constant for A is 0.01 per min. The time taken to reduce the concentration of A from 100 M to 10 M in a batch reactor is ______ min (rounded off to one decimal place).
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The following two reactions describe the chemistry of S(IV) in an aquatic system. Under ideal conditions, the equilibrium constants for reactions (i) and (ii) are 1.3 × 10⁻² M (Kₛ₁) and 6.6 × 10⁻⁸ M (Kₛ₂), respectively. If the pH of the system is 4.0 and the equilibrium concentration of SO₂(aq) is 1.0 M, the equilibrium concentration of SO₃²⁻ is ______ mM (rounded off to one decimal place).
SO₂(aq) ⇌ H⁺ + HSO₃⁻ (i)
HSO₃⁻ ⇌ H⁺ + SO₃²⁻ (ii)
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The calibration graph between absorbance and the concentration of chromate (CrO₄²⁻) in a water sample is shown in the figure. For an absorbance of 0.35 in a water sample, the estimated Cr(VI) concentration is ______ mg/L (rounded off to two decimal places). Use the atomic weight (g/mol) of Cr and O as 52 and 16, respectively.
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In a batch culture experiment, 2 cells of a microorganism were added to a growth medium. During the experiment, a lag phase of 1 hour was first experienced by the added cells, in which no cell multiplication occurred. Afterwards, cells started multiplying exponentially with a doubling time of 1 hour. After total 8 hours of experiment, the number of cells present in the growth medium was ______ (answer in integer).
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You can attempt this question now. Sign in to view the answer key, explanations and discussion.Log in to check answerQuestion 54
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A thermal process, at a specific temperature, results in 2-log₁₀ removal of non-thermotolerant pathogenic microorganisms from a water sample in 20 min. The time needed to achieve 99.999% removal of these microorganisms under similar condition is ______ min (answer in integer).
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