List of top Questions asked in GATE ES

Correctly label the speciation diagram below:


 

A researcher added a 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?
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 4×10^8 m\(^3\) of water is extracted from the aquifer, then the decline in the saturated thickness is ____________ m.
Which of the following is the primary objective of the activated sludge process in wastewater treatment?
Evaluate the following limit:
\[ \lim_{x \to 0} \frac{\ln(1+x)}{2 \sin(x)} \quad \text{(rounded off to two decimal places).} \]
Choose the correct option(s) from the following regarding cumulative toxicity:
Choose the correct option(s) from the following regarding the urban environment:
Methane hydrates have a special crystal structure of water, where methane gas molecules are trapped. Choose the correct option(s) from the following:
Choose the correct option(s) from the following regarding the symbiotic relationships:
Choose the correct option(s) from the following in the plastic waste management:
Stubble burning results in release of particulate matter, volatile organic compounds, oxides of nitrogen and sulfur, to name a few. A researcher is planning to use a conventional Gaussian dispersion model to estimate the contribution of stubble burning in a nearby state to air pollution in New Delhi. Choose the option(s) which could explain the possible limitations in this approach.

Consider the following statements related to nitrification process:
\( (i) \, \text{Electron acceptor type vary depending on whether nitrosomonas or nitrobacter is involved.} \)
\( (ii) \, \text{Predominant carbon source is organic matter.} \)
\( (iii) \, \text{Predominant carbon source is inorganic carbon.} \)
\( (iv) \, \text{Electron donor during conversion of ammonium ions to nitrite ions is ammonium ions.} \)
Choose the correct option(s) from the following:

Choose the correct statement(s) from the following regarding the structure/reproduction of microorganisms:

Consider the following statements: 
(i) Environmental pollutant concentration is generally modeled using lognormal distribution. 
(ii) Environmental pollutant concentration is generally modeled using Poisson distribution. 
(iii) The weekly rate of exceedance of environmental pollutant concentration with regards to a given standard is generally modeled using lognormal distribution. 
(iv) The weekly rate of exceedance of environmental pollutant concentration with regards to a given standard is generally modeled using Poisson distribution. 
Choose the correct option(s) from the following:

Choose the correct option regarding the Basel Convention

Correctly match the sustainable development goal (SDG) with its theme:


 

Which option gives the components that are most likely to be present in the segregated combustible fraction (SCF) separated from raw mixed municipal solid waste (MSW)?
Consider the following statements:

P: According to the National Ambient Air Quality Standards (Central Pollution Control Board, Govt. of India, notification 2009), annual time-weighted average \( \text{PM}_{10} \) standard is more than \( \text{PM}_{2.5} \) standard.

Q: According to the National Air Quality Index released by Govt. of India in 2015, sub-index value of \( \text{PM}_{10} \) can be less than that of \( \text{PM}_{2.5} \).

Choose the correct option from the following:
Multiple effect evaporator is commonly used, in the zero liquid discharge (ZLD) scheme, for ________

Match the following and choose the correct option from the following:

Note: The symbol indicates a stirrer for mixing (not to scale).

For flood routing, consider the following statements:
P: Hydrologic routing method uses continuity equation and momentum equation
Q: Hydraulic routing method uses continuity equation and energy equation
Choose the correct option from the following:
Which one of the following is performed by autotrophic bacteria?
Choose the redox reaction from the following:
Consider the following two series:
\[ \textbf{P: } \sum_{n=1}^{\infty} \frac{1}{n} \qquad \textbf{Q: } \sum_{n=1}^{\infty} \frac{1}{n^2} \]
Choose the correct option from the following:
For the ordinary differential equation \( \frac{d^2y}{dx^2} + 4y = 0 \), the general solution is: