GATE ES year:2025 PYQs & Answers — Page 4

Questions 31–40 of 65. Imported answers require independent review unless marked reviewed.

Methane hydrates have special crystal structure of water, where methane gas molecules are trapped. Choose the correct option(s) from the following

Your answerSelect all correct options. You can choose more than one.

Methane hydrates exist in abundance near the ocean bed, where the pressure is high enough for their existence.

Methane hydrates exist in abundance in the polar regions, where the temperature is low enough for their existence.

Methane hydrates can be a huge source of energy, but can accelerate global warming considerably if the entrapped methane is released to the atmosphere.

Methane hydrates can be a huge source of energy, but difficult to exploit commercially.

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Choose the correct option(s) from the following regarding urban environment

Your answerSelect all correct options. You can choose more than one.

Urban heat island can exacerbate urban flooding by intensifying rainfall intensity.

Urban canyons increase ventilation by trapping heat and thus enhancing urban heat island effect.

Program evaluation and review technique (PERT) is always used to estimate the economic impact of mitigation strategies for urban heat island effect.

In general, land surfaces in urban area emit more long wave radiation compared to those in rural areas, and thus contribute to higher night time temperature.

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Choose the correct option(s) from the following regarding cumulative toxicity

Your answerSelect all correct options. You can choose more than one.

Bioaccumulation is the process by which a living organism keeps on accumulating pollutants in its body due to continuous exposure, whereas, bio-magnification is the process by which higher order organisms accumulate more pollutants than the lower order organisms in a food chain.

Biomagnification is the process by which a living organism keeps on accumulating pollutants in its body due to continuous exposure, whereas, bioaccumulation is the process by which higher order organisms accumulate more pollutants than the lower order organisms in a food chain.

Bioaccumulation and biomagnification are possible with heavy metals, but not with pesticides and pharmaceutical compounds.

Bioaccumulation and biomagnification are possible with heavy metals, pesticides and pharmaceutical compounds.

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is ____________ (rounded off to two decimal places).

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An unconfined aquifer of areal extent 20 km × 20 km has hydraulic conductivity of 4 m/day, porosity of 0.32, and storage coefficient (specific yield) of 0.18. If the initial saturated thickness of the aquifer is 30 m, and 4×10⁸ m³ of water is extracted from the aquifer, then the decline in the saturated thickness is ____________ m. (rounded off to two decimal places)

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A researcher added certain amount of HgCl₂ to water at pH 10. He calculated the expected concentration of mercury in the water. He asked his student to measure the concentration. His student used an instrument that can measure only the free metal, Hg²⁺. The student observed that the concentration measured by him was significantly less than the concentration calculated by the researcher. How can he explain the paradox to the researcher?

Explanation 1: Significant fraction of the mercury would have changed phase from aqueous to gaseous phase, thus leaving less mercury in the water

Explanation 2: Fraction of the mercury added to water would have formed aqueous complexes

Explanation 3: Fraction of the mercury added to water could have precipitated

Choose the correct option from the following

Your answerChoose one option.

only Explanation 1 is correct

Explanations 1 and 2 are correct

Explanations 1 and 3 are correct

Explanations 2 and 3 are correct

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Correctly label the speciation diagram below:

Diagram for Environmental Science and Engineering question 37

Your answerChoose one option.

I= PO₄³⁻, II= HPO₄²⁻, III= H₂PO₄⁻, IV= H₃PO₄

I= H₃PO₄, II= HPO₄²⁻, III= H₂PO₄⁻, IV=PO₄³⁻

I=H₃PO₄, II=H₂PO₄⁻, III=HPO₄²⁻, IV=PO₄³⁻

I= PO₄³⁻, II= H₂PO₄⁻, III= H₃PO₄, IV=HPO₄²⁻

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Consider the following statements on microbial metabolism (i) Utilization of carbon for cell synthesis is termed as anabolism. (ii) During catabolism, adenosine triphosphate (ATP) is converted into adenosine diphosphate (ADP). Choose the correct option from the following

Your answerChoose one option.

(i) and (ii) are correct

(i) and (ii) are incorrect

(i) is correct and (ii) is incorrect

(i) is incorrect and (ii) is correct

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Consider the following figure of an activated sludge process (ASP), depicting the flow (

), substrate (

), and microorganism concentration (

) at various points in the system, where subscripts “0”, “r”, “w”, “e”, and “i” indicate influent, recycle line, wastage, effluent, and flow from aeration tank to settling tank, respectively. Note that influent to the ASP has microbes too. V is volume of aeration tank.

Diagram for Environmental Science and Engineering question 39

Choose the correct option for net rate of formation of microorganisms in the system at steady state, from the following

Your answerChoose one option.

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Consider the following statements (i) Sound pressure changes with distance from the source (ii) Sound power is a property of the source (iii) Sound intensity is sound power per unit volume Choose the correct option from the following

Your answerChoose one option.

(i), (ii), and (iii) are correct

only (i) and (ii) are correct

only (i) and (iii) are correct

only (ii) and (iii) are correct

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GATE ES year:2025 PYQs

Question 31

Question 32

Question 33

Question 34

Question 35

Question 36

Question 37

Question 38

Question 39

Question 40