100+ Free GATE ES Practice Questions

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In a sanitary landfill, the liquid that percolates through and drains from the waste mass, carrying dissolved and suspended contaminants, is called:

Sludge

Leachate

Compost

Landfill gas

to track

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2026 Statistics

Key Facts: GATE ES Exam

65 questions / 100 marks / 180 minutes

GATE ES 2026 exam pattern

gate2026.iitg.ac.in

15 + 13 + 72

General Aptitude + Engineering Mathematics + Subject marks split

GATE 2026 information brochure

Subject sections in the official GATE ES syllabus

GATE 2026 ES syllabus PDF

1/3 and 2/3

Negative marking for 1-mark and 2-mark MCQs (MSQ and NAT have no negative marking)

GATE 2026 marking scheme

100

Free practice questions here

OpenExamPrep

GATE Environmental Science and Engineering (ES) is a 3-hour 65-question 100-mark CBT comprising 15 General Aptitude marks, 13 Engineering Mathematics marks and 72 subject marks across nine ES sections. MCQ items carry 1/3 or 2/3 negative marking; MSQ and NAT items have no negative marking. GATE 2026 is conducted by IIT Guwahati.

Sample GATE ES Practice Questions

Try these sample questions to test your GATE ES exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In the GATE 2026 Environmental Science and Engineering (ES) paper, what is the total number of questions and total marks?

A.55 questions for 100 marks

B.65 questions for 65 marks

C.100 questions for 100 marks

D.65 questions for 100 marks

Explanation: Every GATE paper, including ES, has 65 questions worth a total of 100 marks, completed in a 3-hour computer-based test. The marks are split as 15 General Aptitude, 13 Engineering Mathematics, and 72 subject (ES core) marks.

2For a 2-mark Multiple Choice Question (MCQ) in GATE 2026, what is the negative marking applied for an incorrect answer?

A.2/3 mark deducted

B.No negative marking

C.1/3 mark deducted

D.1 full mark deducted

Explanation: GATE MCQs carry negative marking: 1/3 mark is deducted for a wrong 1-mark MCQ and 2/3 mark for a wrong 2-mark MCQ. Multiple Select Questions (MSQ) and Numerical Answer Type (NAT) questions carry no negative marking.

3Which institute is the Organising Institute conducting GATE 2026?

A.IIT Bombay

B.IIT Kanpur

C.IISc Bangalore

D.IIT Guwahati

Explanation: GATE 2026 is conducted by IIT Guwahati as the Organising Institute on behalf of the National Coordination Board (NCB-GATE). The hosting IIT/IISc rotates each year, and the official portal is gate2026.iitg.ac.in.

4If a 3×3 matrix has eigenvalues 2, 3 and 5, what is the value of its determinant?

A.10

B.30

C.15

D.25

Explanation: The determinant of a matrix equals the product of its eigenvalues. Here 2 × 3 × 5 = 30. (The trace, which is the sum of eigenvalues, would be 10.)

5The Laplace transform of the unit step function u(t) is:

A.1

B.s

C.1/s²

D.1/s

Explanation: The Laplace transform of the unit step function u(t) is 1/s for s > 0. This is a standard transform used in solving linear ODEs, which is part of the GATE ES Mathematics Foundation section.

6By Bayes' theorem, the posterior probability P(A|B) is correctly expressed as:

A.P(B|A)·P(A) / P(B)

B.P(A|B)·P(B) / P(A)

C.P(A)·P(B)

D.P(A) + P(B) − P(A∩B)

Explanation: Bayes' theorem states P(A|B) = P(B|A)·P(A) / P(B), relating the conditional probability of A given B to the reverse conditional and the priors. It is widely used in environmental risk and reliability analysis.

7A statistical hypothesis test comparing the variances of two normally distributed populations uses which test statistic?

A.t-test

B.Chi-square test

C.Z-test

D.F-test

Explanation: The F-test compares two population variances by examining the ratio of sample variances against the F-distribution. The t-test compares means, while the chi-square test handles goodness-of-fit and independence of categorical data.

8For the function f(x) = x³ − 3x, the local maximum occurs at:

A.x = 1

B.x = −1

C.x = 0

D.x = 3

Explanation: Setting f'(x) = 3x² − 3 = 0 gives x = ±1. The second derivative f''(x) = 6x is negative at x = −1 (f'' = −6 < 0), confirming a local maximum there, and positive at x = +1, giving a local minimum.

9Choose the word that is most nearly OPPOSITE in meaning to 'mitigate'.

A.Alleviate

B.Moderate

C.Aggravate

D.Lessen

Explanation: 'Mitigate' means to make less severe or to lessen. Its antonym is 'aggravate', meaning to make worse. This verbal-aptitude item type appears in the GATE General Aptitude section common to all papers.

10A sum of money doubles in 8 years at simple interest. What is the annual rate of interest?

A.8.5%

B.10%

C.12.5%

D.16%

Explanation: For simple interest, doubling means interest equals the principal: P = P × R × T / 100, so 100 = R × 8, giving R = 12.5% per annum. This is a typical quantitative-aptitude item in the GATE GA section.

About the GATE ES Exam

GATE Environmental Science and Engineering (ES) is a dedicated GATE paper used for M.Tech and PhD admissions at IITs, IISc, NITs and IIITs, and increasingly for research and recruitment in environmental, water and pollution-control roles. GATE 2026 is conducted by IIT Guwahati and runs for 180 minutes as a computer-based test with 65 questions worth 100 marks. The paper combines 15 General Aptitude marks, 13 Engineering Mathematics marks, and 72 subject marks spread across nine ES sections: Mathematics Foundation, Environmental Chemistry, Environmental Microbiology, Water Resources and Environmental Hydraulics, Water and Wastewater Treatment and Management, Air and Noise Pollution, Solid and Hazardous Waste Management, Global and Regional Environmental Issues, and Environmental Management and Sustainable Development. Question types include MCQ (with 1/3 or 2/3 negative marking), MSQ (multiple select, no negative marking), and NAT (numerical answer type, no negative marking).

Questions

100 scored questions

Time Limit

180 minutes (3 hours)

Passing Score

Qualifying cutoff varies by year; admissions and recruitment use GATE score and rank rather than a fixed pass mark

Exam Fee

INR 1000 (SC/ST/PwD/Female); INR 2000 (others); INR 500 surcharge during extended registration (IIT Guwahati (GATE 2026 Organising Institute) under the NCB-GATE; the host IIT/IISc rotates annually)

GATE ES Exam Content Outline

15%

General Aptitude

Verbal, quantitative, analytical and spatial aptitude — common to every GATE paper and worth 15 marks (5 one-mark + 5 two-mark questions).

13%

Mathematics Foundation (Engineering Mathematics)

Linear algebra (determinants, matrices, systems of equations, eigenvalues); calculus (limits, continuity, maxima/minima, Taylor series, integration); differential equations and Laplace transform; probability and statistics (Bayes theorem, distributions, correlation, regression, hypothesis testing t/F/chi-square), risk and reliability.

~15%

Environmental Chemistry

Fundamentals (bonding, equilibria, thermodynamics and kinetics, radioactivity); principles of water chemistry (acid-base, buffers, carbonate system, gas solubility, complexation/precipitation/redox, contaminant speciation); soil chemistry (organic matter, N/P/K, cation exchange capacity, base saturation, sodium absorption ratio); atmospheric chemistry (smog, particulate pollution, ozone formation and stratospheric chemistry).

~12%

Environmental Microbiology

Prokaryotic and eukaryotic microorganisms, classification and diversity, role in treatment, bioremediation and biogeochemical cycling; cell chemistry and biology; microbial metabolism (glycolysis, TCA cycle, electron transport, fermentation, enzyme kinetics); growth and control (Monod model, specific growth rate, batch/continuous culture); microbiology and health (pathogens, indicator organisms, MPN and membrane filtration).

~14%

Water Resources and Environmental Hydraulics

Global and surface water resources (hydrological cycle, precipitation, infiltration, evapotranspiration, runoff, unit hydrographs, reservoir and channel routing, rainwater harvesting); groundwater (aquifers, porosity, permeability, transmissivity, storage coefficient, Darcy's law, well hydraulics); environmental hydraulics (fluid properties, pipe and channel flow, specific energy, critical flow, hydraulic jump, channel design).

~15%

Water & Wastewater Treatment and Management

Quality parameters, eutrophication, thermal stratification, oxygen sag curve; water treatment (screening, sedimentation, coagulation, filtration, desalination, disinfection); wastewater sources, population forecasting, sewer design, preliminary/primary/secondary/tertiary treatment, sludge management; industrial effluents, CETP, recycling, zero liquid discharge; reactor kinetics (batch, CMFR, plug-flow).

~13%

Air and Noise Pollution

Atmospheric structure and sources, primary/secondary and criteria pollutants, ambient and source standards, air quality indices; particulate control (settling chambers, cyclones, wet collectors, baghouse filters, electrostatic precipitators); gaseous control (absorption, adsorption, condensation, combustion, catalytic converters, Fick's law); air quality management (dispersion, wind rose, mixing height); noise pollution sources, standards, measurement and control.

~18%

Solid & Hazardous Waste, Global Issues and Sustainable Development

Integrated solid waste management, waste hierarchy and Indian rules; municipal, hazardous, biomedical, plastic and e-waste management, landfilling and leachate; global and regional issues (greenhouse gases, climate change, urban heat islands, acid rain, ozone hole, ecology, biodiversity); environmental management (EMS, ISO 14000, EIA, LCA, risk assessment), environmental law (polluter pays and precautionary principles, Water/Air/EPA Acts, NGT Act 2010), energy-environment nexus and sustainable development goals.

How to Pass the GATE ES Exam

What You Need to Know

Passing score: Qualifying cutoff varies by year; admissions and recruitment use GATE score and rank rather than a fixed pass mark
Exam length: 100 questions
Time limit: 180 minutes (3 hours)
Exam fee: INR 1000 (SC/ST/PwD/Female); INR 2000 (others); INR 500 surcharge during extended registration

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

GATE ES Study Tips from Top Performers

1Master the Mathematics Foundation section first — it is 13 marks, has a high reward-to-effort ratio, and probability/statistics topics recur in microbial growth, reaction kinetics and risk assessment

2Build deep command of Water & Wastewater Treatment and Environmental Chemistry — together they form the single largest scoring block and cut across reactor design, water quality and pollution control

3Learn the standard control technologies cold (ESP, cyclone, baghouse for particulates; absorption, adsorption and catalytic converters for gases) and the matching air-quality concepts (NAAQS, primary vs secondary pollutants, dispersion)

4Memorise the key Indian environmental statutes and bodies — Water Act 1974, Air Act 1981, Environment (Protection) Act 1986, NGT Act 2010, CPCB, ISO 14000, EIA, LCA — these are quick, high-yield management-section marks

5Solve previous-year GATE ES papers and at least 15–20 full-length 3-hour CBT mocks in the final months; pacing across mixed NAT/MSQ/MCQ items is critical given 65 questions

6Use the official GATE virtual calculator on gate2026.iitg.ac.in before the exam — its layout differs from common physical calculators and slows unprepared candidates

Frequently Asked Questions

What is the GATE ES 2026 exam pattern?

GATE Environmental Science and Engineering 2026 is a 3-hour computer-based test with 65 questions worth 100 marks. The paper combines 15 marks of General Aptitude, 13 marks of Engineering Mathematics (Mathematics Foundation), and 72 marks of subject questions spanning nine ES sections from environmental chemistry and microbiology to water, air, noise and waste management. Questions are MCQ, MSQ (multiple-select) or NAT (numerical answer type).

What is the marking scheme and negative marking in GATE ES?

MCQs carry 1 or 2 marks with negative marking of 1/3 or 2/3 respectively for a wrong answer. Multiple Select Questions (MSQ) and Numerical Answer Type (NAT) questions carry 1 or 2 marks with no negative marking, and MSQs give no partial credit. Unanswered questions earn zero marks.

Who conducts GATE 2026 and how do I register?

GATE 2026 is conducted by IIT Guwahati on behalf of the National Coordination Board GATE (NCB-GATE), MoE. Registration is through the GOAPS portal on gate2026.iitg.ac.in; the application window typically opens in late August and closes in early October 2025, with an extended (surcharge) window thereafter and exams held on 7, 8, 14 and 15 February 2026.

What are the nine sections of the GATE ES syllabus?

The GATE ES subject syllabus has nine sections: Mathematics Foundation; Environmental Chemistry; Environmental Microbiology; Water Resources and Environmental Hydraulics; Water and Wastewater Treatment and Management; Air and Noise Pollution; Solid and Hazardous Waste Management; Global and Regional Environmental Issues; and Environmental Management and Sustainable Development. General Aptitude (15 marks) is common to all GATE papers.

What are the high-weightage topics in GATE ES?

Water and wastewater treatment, environmental chemistry, and air pollution control are consistently heavy-scoring areas, along with Mathematics Foundation (13 marks). Environmental microbiology, water resources and environmental hydraulics, and the management/sustainability sections (EIA, ISO 14000, environmental law) also carry meaningful weight, so a broad, balanced preparation across all nine sections is advised.

Is the GATE ES score useful and how long is it valid?

Yes. The GATE ES score is used for M.Tech and PhD admissions at IITs, IISc, NITs and IIITs in environmental engineering and allied programmes, for research fellowships, and for some recruitment in environmental and water-sector roles. The GATE 2026 score is valid for 3 years from the date of result announcement.

Can I use a calculator in GATE ES?

Yes — but only the virtual scientific calculator provided on-screen in the GATE CBT interface. Physical calculators, mobile phones, smart watches and any digital aids are strictly prohibited. Practising with the official online virtual calculator available on the GATE website ahead of the exam is highly recommended.

100+ Free GATE ES Practice Questions

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