Model Paper (GATE-2021) : ES Environmental Science and Engineering

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Q1. to Q22. are MCQ where only one answer is correct. Each question carries one mark.

Q. 1 The relative error in the calculation of the volume of a sphere is nearly ________ times the relative error in the measurement of the radius.

(a) Three

(b) Two

(c) Five

(d) Six


Q. 2 A river is 24 wide. The depth Z in meters at a distance x m from one bank is given by the following table:

The Rounding off to One Decimal Place

The area of river cross section using simpson՚s rule is ________ (rounding off to one decimal place) .






Q. 3 What are the values of and , respectively, in the following balance redox reaction:






Q. 4 If mass, number concentration of will always be:


(b) Depends on size distribution




Q. 5 Which of the following species have very long lifetime in the atmosphere?


(a) 1 and 4

(b) 3 and 4

(c) 2 and 3

(d) 1 and 4


Q. 6 The waste can be categorized as ‘hazardous’ if

(a) It burns at temperatures more than

(b) It is above

(c) It reacts slowly with water

(d) All of the above

Q. 7 A deep trickling filter with a diameter of is operated with a recirculation ratio of . The raw wastewater flow rate is and the BOD of the raw sewage is . Assuming that the primary tank BOD removal efficiency is , Compute organic load on the trickling filter.





Q. 8 If the average annual rainfall and evaporation over land masses and oceans of the earth are considered, it would be found that

(a) Over the oceans about more water evaporates than what falls back on them as precipitation

(b) Over the land masses the annual evaporation is the same as the annual precipitation

(c) Over the oceans about more rain falls than what is evaporated

(d) About more evaporates from the oceans than what falls back on them as precipitation

Q. 9 There are four stages in the life of a lake:

(i) Eutrophic

(ii) Oligotrophic,

(iii) Mesotrophic and

(iv) Senescent.

Which one is the correct order among the following:

(a) (ii) , (i) , (iii) and (iv)

(b) (ii) , (iv) , (iii) and (i)

(c) (iii) , (iv) , (ii) and (i)

(d) (ii) , (iii) , (i) and (iv)

Q. 10 If specific yield and Specific retention, then


(b) Porosity



Q. 11 Sustainable development can be thought of in terms of three spheres i.e..

(a) Environment, Economy and Ecology

(b) Environment, Ecology and Society

(c) Environment, Economy and Society

(d) Environment, Economy, and equity

Q. 12 If in a city, the maximum daily water draft is 25MLD, fire draft is 35MLD and maximum hourly draft is 40 MLD, what is the coincident draft?





Q. 13 Permanent hardness from water can be removed by the addition of

(a) Potassium Permanganate

(b) Lime

(c) Sodium Bicarbonate

(d) Soda ash

Q. 14 According to solid waste Management Rules (2016) in India, all industrial units within ________ of RDF production plants shall replace at least of their fuel by RDF.



(c) None of these


Q. 15 Solar energy reaching the Earth is approximately:





Q. 16 In ISO 14000 series of Standards, which one does not belong to ‘Organization or process’ standards:

(a) Environmental Management Standards

(b) Environmental aspects in product standards

(c) Environmental performance evaluation

(d) Environmental audit

Q. 17 The point of inflection on the recession limb of a hydrograph represents

(a) Peak runoff rate

(b) The end of base flow

(c) The condition of maximum storage in the catchment

(d) The Cessation of rainfall

Q. 18 Which of the following measures can be used for reducing road traffic noise?

(i) Use of noise barriers,

(ii) Limiting vehicle speeds,

(iii) Alteration of road surface

(a) All of the above

(b) I and iii

(c) ii and iii

(d) I and ii

Q. 19 Which of the following are considered “criteria air pollutants”






Q. 20India՚s energy needs are heavily dependent on coal-based thermal power plants, which are also one of the most polluting sources. Which of the following is the most dominant air Pollutants that power plants emit?





Q. 21 A peptide bond is formed between two amino acids by the reaction of the one amino acid with the ________ of the other.

(a) R group/carboxyl group

(b) R group/R group

(c) of the amino group/ of the carboxyl group

(d) group/central carbon atom

Q. 22 Which of the following is true, with respect to a catalytic converter, which is used for controlling gaseous exhaust emissions in automobiles?

(a) It oxidizes and reduces

(b) It oxidizes and reduces

(c) It oxidizes and reduces

(d) It oxidizes and reduces

Q. 23. to Q26. are NAT. Each question carries one mark.

Q. 23 A sewage sample having of is diluted to and incubated for 5 days at . If the dissolved oxygen content after 5 days is found to be , the initial content of the diluted sample was ________ . Your response should have no decimal digit.

Q. 24 If the initial volume of the municipal solid waste is and after compaction it is reduced to . The waste compaction ratio will be ________. Your response should have no decimal digit.

Q. 25 For the same solids content, if the volume of sludge with moisture content of is , then the volume of sludge with moisture content of will be________ . Your response should have no decimal digit.

Q. 26. to Q38. are MCQ type, where only one answer is correct. Each question carries two marks.

Q. 26 Particular solution to the differential equation , given when , is ________.





Q. 27 The value of is ________





Q. 28 Assuming the unitless normalized values of turbidity and heavy metal concentration in river water are highly associated and may be represented by the random variables X and Y, respectively. The joint probability density function of these variables is given by

The probability value, is ________.





Q. 29 The rainfall in three successive periods is and . If the initial loss is and, the surface runoff resulting from this storm is , the index of infiltration for this storm is ________.





Q. 30 Two reservoirs are connected by two pipes M and N of identical diameter and length, in parallel. If the friction factor of M is times that of N, the ratio of the discharge in A to that of in B is ________.





Q. 31 A hydraulic jump takes place in a horizontal rectangular channel from a depth of to . The discharge in the channel in eter width is ________.





Q. 32 The stream function is a two-dimensional flow field is given by . The magnitude of the velocity at point is ________.






Q. 33 A sample of water has an initial of . To titrate the sample to 4.5, milliliters of is required. Suppose the equivalence point is reached at milliliters of acid. The total alkalinity of the water and its species (i.e.. , and ) in milligrams per liter as will be as follows (in the same order) :





Q. 34 The average per capita energy consumption of USA is about

(a) times that of India

(b) 5 times that of global average

(c) (Area of USA/area of World) time that of the world

(d) 50 times that of global average

Q. 35 The latitudinal diversity gradient is defined as the decrease in the number of species from the equator to the poles. This can result from:

(a) Greater seasonal variation at the poles

(b) Greater speciation rates at the poles

(c) Greater land mass at the poles

(d) Greater energy input at the poles

Q. 36 Arrange the following in correct order for particulate matter (PM) measurements.

The Particulate Matter Measurment

(a) 1,3, 4,2

(b) 3,1, 4,2

(c) 3,4, 1,2

(d) 1,4, 3,2

Q. 37 Two noise sources produce 65 and 60 dB of noise for the same duration. What will be the resulting noise (in dB) that a person exposed to both the sources will experience?





Q. 38 A climate scientist notices a trend in atmospheric concentrations (in ppm) at a research station. Although overall is rising over decades, there are intra-annual fluctuations, as shown in the figure below.

The Intra-Annual Fluctuations

These fluctuations can be attributed to

(a) Oscillations due to events

(b) Rising sea levels due to melting of polar ice-caps

(c) Seasonal trends in photosynthesis and respiration

(d) Burning of fossil fuels by automobiles and industry

Q. 39 to Q50. are MSQ type, where one or more answers are correct. Each question carries two marks.

Q. 39 TDS in wastewater

(a) Is expected to show a good correlation with conductivity

(b) May be caused by undissociated organic substances

(c) May be caused by cations and anions

(d) Is expected to show a good correlation with alkalinity

Q. 40 In Monod՚s for microbial growth relating the specific growth rate to substrate concentration (S) with and as model parameters:

(a) The lue is an absolute maximum value of for the chosen microbe that is unaffected by the system conditions.

(b) The Monod model is not applicable for inhibitory substrates

(c) For any microbe, affected by the choice of substrate

(d) Both and can be expressed in

Q. 41 The titration used for estimating hardness uses

(a) Phenolphthalein as indicator

(b) Uses sodium thiosulphate as the titrant

(c) Uses ethylenediaminetetraacetic acid as the titrant

(d) Eriochrome Black-T as indicator

Q. 42 The combination that correctly matches an organelle in a microbe in Group-I to its function in Group-II

Table of Group - I and Group-II
(i)Mitochondria(a)Antibiotic Resistance
(ii)Chloroplast(b)Shape and rigidity
(iii)Cell Wall(c)Respiration

(a) I and b:

(b) ii and a:

(c) iv and a

(d) iii and b;

Q. 43 Identify the Incorrect Choices pertaining to the polysaccharides, starch, and cellulose

(a) In both starch and cellulose, the monomers are joined by identical bonds

(b) The component monomers in starch and cellulose are enantiomers

(c) The component monomers in starch and cellulose are stereoisomers

(d) The component monomers in starch and cellulose are anomers

Q. 44 Identify the correct Choices pertaining to the process of glycolysis in microorganisms

(a) Involves a-ketoglutarate as an intermediate

(b) Involves substrate level phosphorylation

(c) The first two steps are identical in all microorganisms but the third step differs

(d) Is identical in all microorganisms

Q. 45 Which of the following traits are not necessary for a good indicator organism

(a) It should be non-pathogenic

(b) It must possess greater resistance to disinfectants compared to pathogenic microbes

(c) It should be a Gram-negative rod-shape bacterium

(d) It should have the ability to multiply in the environment

Q. 46 With regard to segregation and treatment of municipal solid waste, which of the statements are correct?

(a) Trommels are used to shred the waste

(b) Stoners are used for the separation of heavy grit from lighter material

(c) Composting of biodegradable waste is a produces biogas and manure

(d) Aluminum separation from solid wastes can be accomplished by eddy current separators

Q. 47 The plastic waste can be used for following purposes:

(a) Biogas production

(b) Manure production

(c) Road construction

(d) Generation of syn gas

Q. 48 Identify the tasks that are included in an Impact assessment.

(a) All the data collection, analyses, and developed plans summarized together in a well-structured and concise document

(b) A detailed assessment of the planned project and selected alternatives compared to the baseline conditions

(c) Quantitative descriptions such as indicating the cubic meters of water withdrawn, sewage produced, and pollutants released

(d) Qualitative descriptions measuring high, medium, and low impacts

Q. 49 Identify the choices that pertain to principles inherent in international law:

(a) The polluter pays principle

(b) Precautionary principle

(c) Principle of non-discrimination

(d) Principle of intergenerational equity

Q. 50 Identify the correct choice pertaining to DNA and RNA nucleotides

(a) In both DNA and RNA nucleotides, the sugar is a pentose sugar that is structurally different at two positions

(b) The pyrimidine base uracil is present only in RNA

(c) The nitrogenous base in both DNA and RNA nucleotides contain one or two heterocyclic rings

(d) The sugar is identical in both DNA and RNA nucleotides but the nitrogenous base differs

Q51. to Q55. are NAT. Each question carries two marks.

Q. 51 A toxicological analysis of particulate matter requires a minimum of mass. You decide to use a low volume air sampler f a household with a smoker has average indoor PM levels, the sample would have to be collected for ________ hours. Your response should have one digit after decimal point.

Q. 52 The capacity of a septic tank is to be determined using the following information: No. of people ; sewage generation per capita per liters; desludging period year, detention time , rate of sludge deposit in tank liters/capita/year, length: width ratio capacity of tank will be ________ . Your response should have no decimal digit.

Q. 53 A sanitary landfill has the following specifications: Design life of the site years; MSW generation rate N/person/day; municipal solid waste (MSW) compacted unit weight ; Average fill depth ; Population MSW to cover ratio . The area required for sanitary landfill will be ________ hectares. Your response should have no decimal digit.

Q. 54 Suppose out of rates exposed to a potential carcinogen develop tumors. A control group of rates not exposed to the carcinogen develops only tumors. Based on these data, the Attributable (additional) Risk is ________. Your response should have three decimal digits.

Q. 55 With a chlorine dose of of the bacteria are killed in . If Chick՚s law, is valid the rate of kill of bacteria with this dose, rounded off to the nearest integer will be ________ min.