Jkssb field assistant solved question paper download now held on 21 May 2026 by home academy

 

​JKSSB Field Assistant Question Paper 2026 by Home Academy

​1. Which of the following international conferences is correctly matched with its primary outcome?

A) Stockholm Conference (1972) - adopted the Kyoto Protocol

B) Rio Earth Summit (1992) - adopted Agenda 21 and the Convention on Biological Diversity

C) Paris Agreement (2015) - first global agreement on ozone layer protection

D) Montreal Protocol (1997) - focused on climate change mitigation

​2. Which of the following is not a Multilateral Environmental Agreement (MEA) related to climate change?

A) UNFCCC

B) Kyoto Protocol

C) Paris Agreement

D) CITES (Convention on International Trade in Endangered Species)

​3. Which of the following correctly describes an abiotic component of the environment?

A) Green plants synthesizing organic matter through photosynthesis

B) Wind patterns influencing erosion and sediment transport

C) Decomposer microbes breaking down organic waste

D) Predation of deer by tiger in a forest ecosystem

​4. Which of the following best describes a biotic environment?

A) Air, water, and soil

B) Sunlight, temperature, and topography

C) Plants, animals, and microorganisms

D) Minerals and rocks

​5. Which of the following is not an example of a non-renewable resource?

A) Coal

B) Petroleum

C) Groundwater in a recharge-limited aquifer

D) Solar energy

​6. Over-exploitation of non-renewable resources primarily leads to:

A) Decrease in biodiversity only

B) Increased photosynthetic rates in forests

C) Depletion of resource stock and long-term environmental degradation

D) Stabilization of atmospheric temperature

​7. Which of the following conditions is least likely to be caused by long-term exposure to air pollution in urban areas?

A) Chronic bronchitis

B) Ischemic heart disease

C) Vitamin-D deficiency

D) Asthma exacerbations

​8. Which of the following pollutants is most strongly associated with methemoglobinemia (blue-baby syndrome) in infants?

A) Sulfur dioxide (\text{SO}_2)

B) Nitrate (\text{NO}_3^-) in drinking water

C) Lead (\text{Pb}) in soil

D) Ozone (\text{O}_3) in air

​9. The National Green Tribunal (NGT) was established under:

A) The Environment (Protection) Act, 1986

B) The National Green Tribunal Act, 2010

C) The Water (Prevention and Control of Pollution) Act, 1974

D) The Air (Prevention and Control of Pollution) Act, 1981

​10. Which of the following environmental laws is not explicitly covered under the NGT Act for adjudicating disputes?

A) Forest (Conservation) Act, 1980

B) Wildlife (Protection) Act, 1972

C) Environment (Protection) Act, 1986

D) Biological Diversity Act, 2002

​11. Consider the following statements regarding abiotic and biotic components of the environment:

I. Abiotic components are governed primarily by physical and chemical laws and do not reproduce.

II. Biotic components include only plants and animals, excluding microorganisms.

III. Interaction between abiotic and biotic components determines productivity and carrying capacity of an ecosystem.

Which of the statements given above is/are correct?

A) I and II only

B) I and III only

C) II and III only

D) I, II and III

​12. Consider the following statements regarding the National Green Tribunal (NGT) Act, 2010:

I. NGT primarily hears civil disputes arising under specified environmental enactments.

II. Orders of NGT are appealable only before the respective High Court.

III. NGT can frame new criminal substantive law and independently prosecute offenders under the IPC.

Which of the statements given above is/are correct?

A) I only

B) I and II only

C) II and III only

D) I, II and III

​13. Consider the following statements regarding non-renewable resources and health hazards:

I. Coal and petroleum are non-renewable resources whose extraction often leads to land subsidence and acid mine drainage.

II. Long-term exposure to groundwater contaminated with arsenic is associated with skin lesions and black-foot disease.

III. Indoor air pollution from solid-fuel stoves does not cause any significant health burden in developing countries.

Which of the statements given above is/are correct?

A) I and II only

B) I and III only

C) II and III only

D) I, II and III

​14. Consider the following statements regarding pollution indices and environmental events:

I. The Air Quality Index (AQI) in India is based on the concentration of multiple pollutants including \text{PM}_{2.5}, \text{PM}_{10}, \text{NO}_2, and \text{CO}.

II. The Pollutant Standards Index (PSI) is used in India as the primary national air quality index.

III. The Montreal Protocol (1987) is an international agreement aimed at protecting the ozone layer by phasing out ozone depleting substances.

Which of the statements given above is/are correct?

A) I and II only

B) I and III only

C) II and III only

D) I, II and III

​15. Match List-I (Pollution Type) with List-II (Associated Health Hazard / Effect) and select the correct code:

List-I

i. Air (\text{PM}_{2.5})

ii. Water (Nitrates)

iii. Land (Heavy Metals)

iv. Noise

​List-II

a. Methemoglobinemia

b. Hearing loss

c. Respiratory diseases

d. Neurological disorders

​Choose the correct match:

A) i-c, ii-a, iii-d, iv-b

B) i-a, ii-c, iii-b, iv-d

C) i-d, ii-b, iii-c, iv-a

D) i-c, ii-d, iii-a, iv-b

​16. Match List-I (Environmental Agreement) with List-II (Year / Description) and select the correct code:

List-I

i. Stockholm

ii. Rio

iii. Kyoto

iv. Paris

​List-II

a. 1997 targets

b. 1992 Agenda 21

c. 1972 first UN conf

d. 2015 global agreement

​Choose the correct match:

A) i-c, ii-b, iii-a, iv-d

B) i-b, ii-c, iii-d, iv-a

C) i-c, ii-a, iii-b, iv-d

D) i-a, ii-b, iii-c, iv-d

​17. Match List-I (Resource Type) with List-II (Example) and select the correct code:

List-I

i. Non-renewable

ii. Renewable

iii. Abiotic

iv. Biotic

​List-II

a. Solar

b. Petroleum

c. Topography

d. Forest

​Choose the correct match:

A) i-b, ii-a, iii-c, iv-d

B) i-a, ii-b, iii-d, iv-c

C) i-b, ii-c, iii-a, iv-d

D) i-d, ii-a, iii-b, iv-c

​18. Match List-I (Pollution Index / Tool) with List-II (Purpose) and select the correct code:

List-I

i. AQI

ii. WQI

iii. BOD

iv. PSI

​List-II

a. Organic pollution in water

b. Overall water quality

c. Urban air quality

d. Old US index

​Choose the correct match:

A) i-c, ii-b, iii-a, iv-d

B) i-b, ii-c, iii-d, iv-a

C) i-d, ii-a, iii-c, iv-b

D) i-c, ii-a, iii-b, iv-d

​19. Arrange the following environmental events in chronological order (earliest first):

I. Earth Summit (Rio Earth Summit)

II. Stockholm Conference on Human Environment

III. Adoption of the Kyoto Protocol

IV. Paris Agreement on Climate Change

Choose the correct order:

A) I-II-III-IV

B) II-I-III-IV

C) II-III-I-IV

D) I-III-II-IV

​20. Arrange the following environment-related days in chronological order within a single calendar year (earliest first):

I. World Health Day

II. World Environment Day

III. Earth Day

IV. World Ozone Day

Choose the correct order:

A) I-III-II-IV

B) III-I-II-IV

C) I-II-III-IV

D) III-IV-I-II

​21. The quantity of sewage generated in a town is generally estimated as approximately:

A) 20-30% of per-capita water supplied

B) 50-60% of per-capita water supplied

C) 75-85% of per-capita water supplied

D) 100% of per-capita water supplied

​22. For proper design of sewerage components, the design period is normally taken as:

A) 5-10 years for sewers and 1-5 years for treatment works

B) 10-15 years for sewers and 5-10 years for treatment works

C) 20-30 years for sewers and 15-25 years for treatment works

D) 40-50 years for both sewers and treatment works

​23. In a conventional activated sludge process, the secondary clarifier is primarily used for:

A) Aeration of mixed liquor

B) Settling and separation of biomass (sludge) from treated effluent

C) Equalization of flow and BOD

D) Disinfection of effluent

​24. The Rotating Biological Contactor (RBC) is a type of:

A) Suspended-growth biological system

B) Attached-growth biological system

C) Physical sedimentation unit

D) Chemical coagulation unit

​25. Which of the following unit operations removes fine suspended solids and colloidal particles by chemical destabilization and formation of flocs?

A) Sedimentation

B) Filtration

C) Coagulation and flocculation

D) Disinfection

​26. In a UASB (Upflow Anaerobic Sludge Blanket) reactor, the key feature is:

A) Naturally formed granular sludge bed through which wastewater flows upward

B) Aeration provided through mechanical diffusers

C) Use of rotating media to support biomass

D) Only chemical precipitation of organics

​27. Which of the following industrial wastewaters is characterized by high BOD, high solids, and high alkalinity, and often requires neutralization and equalization before treatment?

A) Textile

B) Tannery

C) Dairy

D) Distillery

​28. In a Sequencing Batch Reactor (SBR), the operational sequence within each cycle is:

A) Fill \rightarrow Aerate \rightarrow Settle \rightarrow Decant \rightarrow Idle

B) Aerate \rightarrow Fill \rightarrow Decant \rightarrow Idle \rightarrow Settle

C) Settle \rightarrow Fill \rightarrow Idle \rightarrow Aerate \rightarrow Decant

D) Idle \rightarrow Aerate \rightarrow Fill \rightarrow Settle \rightarrow Decant

​29. Which of the following pumps is most commonly used for pumping raw sewage containing suspended solids?

A) Reciprocating pump

B) Diaphragm pump

C) Pneumatic ejector

D) Centrifugal pump with open impeller

​30. Pumping stations for sewage are generally located:

A) Only at the extreme downstream end of the sewer network

B) At depression points, along the sewer line, and at the sewage treatment plant head

C) Only at the start of the sewer line

D) At random locations without any pattern

​31. Consider the following statements about sewage discharge and design periods:

I. Per-capita sewage generated is generally taken as about 75-85% of per-capita water supplied.

II. The average daily sewage flow is sufficient for sizing all components of the sewerage system without any peak-factor consideration.

III. Design periods for sewers are usually longer than those for treatment-plant components.

Which of the statements given above is/are correct?

A) I and II only

B) I and III only

C) II and III only

D) I, II and III

​32. Consider the following statements regarding unit operations in water and wastewater treatment:

I. Coagulation neutralizes the surface charge of colloids, while flocculation promotes their aggregation.

II. Sedimentation tanks are designed mainly for the removal of dissolved organics.

III. Adsorption (e.g., using activated carbon) is effective for removing color, taste- and odor compounds, and some micropollutants.

Which of the statements given above is/are correct?

A) I and II only

B) I and III only

C) II and III only

D) I, II and III

​33. Consider the following statements regarding biological treatment systems:

I. Trickling filters are attached-growth systems in which wastewater trickles over a media bed.

II. Sequencing Batch Reactor (SBR) is a suspended-growth system that operates in time-phased cycles in a single tank.

III. Anaerobic filters are used only for treating sewage and not for industrial effluents.

Which of the statements given above is/are correct?

A) I and II only

B) I and III only

C) II and III only

D) I, II and III

​34. Consider the following statements regarding nitrification and denitrification:

I. Nitrification converts ammonium (\text{NH}_4^+) to nitrate (\text{NO}_3^-) under aerobic conditions.

II. Denitrification converts nitrate (\text{NO}_3^-) to nitrogen gas (\text{N}_2) under anaerobic/anoxic conditions.

III. Both processes are performed by the same group of autotrophic bacteria.

Which of the statements given above is/are correct?

A) I and II only

B) I and III only

C) II and III only

D) I, II and III

​35. Match List-I (Unit Process) with List-II (Primary Purpose) and select the correct code:

List-I

i. Equalization

ii. Aeration

iii. Adsorption

iv. Disinfection

​List-II

a. Pathogen removal

b. Reduction of variations

c. Supply oxygen

d. Removal of color/odour

​Choose the correct match:

A) i-b, ii-c, iii-d, iv-a

B) i-c, ii-b, iii-a, iv-d

C) i-b, ii-a, iii-d, iv-c

D) i-d, ii-c, iii-b, iv-a

​36. Match List-I (Biological System) with List-II (Type of Growth / Configuration) and select the correct code:

List-I

i. Activated Sludge

ii. Trickling Filter

iii. RBC

iv. UASB

​List-II

a. Attached (rotating)

b. Attached (stationary)

c. Suspended (aeration+clarifier)

d. Anaerobic granular bed

​Choose the correct match:

A) i-c, ii-b, iii-a, iv-d

B) i-b, ii-c, iii-a, iv-d

C) i-c, ii-a, iii-b, iv-d

D) i-d, ii-b, iii-c, iv-a

​37. Match List-I (Industrial Effluent) with List-II (Characteristics / Major Issues) and select the correct code:

List-I

i. Textile

ii. Tannery

iii. Dairy

iv. Distillery

​List-II

a. Salinity/Anaerobic

b. Nutrients/Fats

c. Colour/Dyes

d. Organics/Chromium

​Choose the correct match:

A) i-c, ii-d, iii-b, iv-a

B) i-d, ii-c, iii-a, iv-b

C) i-c, ii-b, iii-d, iv-a

D) i-a, ii-c, iii-b, iv-d

​38. Match List-I (Pump Type) with List-II (Typical Use) and select the correct code:

List-I

i. Centrifugal

ii. Reciprocating

iii. Diaphragm

iv. Pneumatic

​List-II

a. Viscous sludge

b. Raw sewage

c. Small-scale lifting

d. Dosing chemicals

​Choose the correct match:

A) i-b, ii-a, iii-d, iv-c

B) i-a, ii-b, iii-c, iv-d

C) i-b, ii-d, iii-c, iv-a

D) i-c, ii-a, iii-b, iv-d

​39. Arrange the following steps in a conventional biological wastewater treatment train in correct order (flow direction):

I. Secondary clarifier

II. Aeration tank

III. Primary clarifier

IV. Coagulation flocculation settling (if included)

Choose the correct sequence:

A) IV-III-II-I

B) III-IV-II-I

C) IV-II-I-III

D) III-II-I-IV

​40. Arrange the following biological treatment configurations in the order of increasing level of process control / sophistication (simplest first):

I. Wastewater stabilization ponds

II. Trickling filter

III. Conventional activated sludge process

IV. Sequencing Batch Reactor (SBR)

Choose the correct sequence:

A) I-II-III-IV

B) II-I-III-IV

C) I-III-II-IV

D) IV-III-II-I

​41. Which of the following is primarily a physical characteristic of water or sewage?

A) pH

B) COD

C) BOD

D) Turbidity

​42. High BOD in wastewater indicates:

A) High inorganic salt content

B) High concentration of biodegradable organic matter

C) High dissolved oxygen concentration

D) High alkalinity

Here is the official answer key with detailed explanations for each question from the paper.

​Answer Key & Explanations

​1. Which of the following international conferences is correctly matched with its primary outcome?

• ​Correct Answer: B) Rio Earth Summit (1992) - adopted Agenda 21 and the Convention on Biological Diversity
• ​Explanation: The United Nations Conference on Environment and Development (UNCED), also known as the Rio Earth Summit, was held in 1992 and successfully resulted in Agenda 21, the Rio Declaration, and opened the Convention on Biological Diversity (CBD) for signing.
  • ​Why others are wrong: The Stockholm Conference happened in 1972, way before the Kyoto Protocol (1997). The Paris Agreement (2015) is about climate change, not ozone layer protection (which is the Montreal Protocol). The Montreal Protocol was signed in 1987, not 1997.

​2. Which of the following is not a Multilateral Environmental Agreement (MEA) related to climate change?

• ​Correct Answer: D) CITES (Convention on International Trade in Endangered Species)
• ​Explanation: CITES is an international agreement between governments focused on ensuring that international trade in specimens of wild animals and plants does not threaten their survival. It targets biodiversity preservation and wildlife protection rather than atmospheric climate change mitigation. UNFCCC, Kyoto, and Paris are all core pillars of global climate change governance.

​3. Which of the following correctly describes an abiotic component of the environment?

• ​Correct Answer: B) Wind patterns influencing erosion and sediment transport
• ​Explanation: Abiotic components are the non-living chemical and physical factors in the environment. Wind, water currents, temperature, and soil structure fall directly under this category.
  • ​Why others are wrong: Green plants (producers), decomposer microbes, and tigers/deer (predators/prey) are all living organisms, making them biotic components.

​4. Which of the following best describes a biotic environment?

• ​Correct Answer: C) Plants, animals, and microorganisms
• ​Explanation: The term "biotic" strictly refers to the living components of an ecosystem. This includes all flora (plants), fauna (animals), and micro-flora/fauna (bacteria, fungi, and protozoa). All other options list physical, non-living elements like air, soil, rocks, and minerals.

​5. Which of the following is not an example of a non-renewable resource?

• ​Correct Answer: D) Solar energy
• ​Explanation: Solar energy is an inexhaustible, renewable resource derived from the sun's nuclear fusion processes, meaning it does not deplete with human consumption.
  • ​Why others are wrong: Coal and petroleum take millions of years to form and are strictly non-renewable. Groundwater in a "recharge-limited" aquifer means it is being drawn out faster than nature can replenish it, effectively making it a non-renewable stock.

​6. Over-exploitation of non-renewable resources primarily leads to:

• ​Correct Answer: C) Depletion of resource stock and long-term environmental degradation
• ​Explanation: Because non-renewable resources exist in finite quantities, consuming them past their natural replenishment rate leads to irreversible exhaustion of their reserves. Furthermore, the extraction processes (mining, drilling) cause structural environmental damage, habitat loss, and pollution.

​7. Which of the following conditions is least likely to be caused by long-term exposure to air pollution in urban areas?

• ​Correct Answer: C) Vitamin-D deficiency
• ​Explanation: Vitamin D deficiency is primarily caused by a lack of direct sunlight exposure to the skin or dietary deficiencies. While dense smog can technically filter out some UV rays, it is not categorized as a primary baseline clinical health consequence of urban ambient air pollution.
  • ​Why others are wrong: Chronic bronchitis, ischemic heart disease, and asthma exacerbations are classic, universally documented medical consequences of prolonged exposure to particulate matter (\text{PM}_{2.5} and \text{PM}_{10}) and toxic gases.

​8. Which of the following pollutants is most strongly associated with methemoglobinemia (blue-baby syndrome) in infants?

• ​Correct Answer: B) Nitrate (\text{NO}_3^-) in drinking water
• ​Explanation: When infants ingest water high in nitrates, their digestive systems convert the nitrates into nitrites. These nitrites bind to hemoglobin, forming methemoglobin, which cannot effectively release oxygen to body tissues. This causes clinical hypoxia, giving the infant's skin a blue tint.

​9. The National Green Tribunal (NGT) was established under:

• ​Correct Answer: B) The National Green Tribunal Act, 2010
• ​Explanation: The NGT was set up on October 18, 2010, under the specific legislative mandate of the National Green Tribunal Act, 2010, enacted by the Parliament of India for the expeditious disposal of environmental cases.

​10. Which of the following environmental laws is not explicitly covered under the NGT Act for adjudicating disputes?

• ​Correct Answer: B) Wildlife (Protection) Act, 1972
• ​Explanation: Schedule I of the NGT Act lists 7 specific environmental laws under which the tribunal has jurisdiction to hear civil cases. Notably, the Wildlife (Protection) Act, 1972 and the Indian Forest Act, 1927 are explicitly excluded from its ambit. The Forest (Conservation) Act, Environment (Protection) Act, and Biological Diversity Act are all explicitly covered.

​11. Consider the following statements regarding abiotic and biotic components of the environment:

• ​Correct Answer: B) I and III only
• ​Explanation: * Statement I is correct: Abiotic components are non-living physical/chemical systems that obey thermodynamic and physical laws and do not undergo biological reproduction.
  • ​Statement II is incorrect: Biotic factors include all living things, which heavily encompasses microorganisms (bacteria, fungi, viruses) alongside plants and animals.
  • ​Statement III is correct: The dynamic exchange of energy and nutrients between the living community (biotic) and the physical environment (abiotic) strictly dictates ecosystem productivity and carrying limits.

​12. Consider the following statements regarding the National Green Tribunal (NGT) Act, 2010:

• ​Correct Answer: A) I only
• ​Explanation: * Statement I is correct: The NGT is explicitly a civil tribunal established to handle civil disputes involving substantial questions relating to the environment.
  • ​Statement II is incorrect: Any award, decision, or order of the NGT is directly appealable to the Supreme Court of India (under Section 22 of the NGT Act), not the High Courts.
  • ​Statement III is incorrect: The NGT cannot create new criminal laws nor independently prosecute criminal acts under the Indian Penal Code; it works within existing statutory environmental frameworks.

​13. Consider the following statements regarding non-renewable resources and health hazards:

• ​Correct Answer: A) I and II only
• ​Explanation: * Statement I is correct: Subsurface mining of coal and petroleum frequently causes geotechnical failures leading to land subsidence, while sulfur-bearing minerals exposed during mining lead to hazardous acid mine drainage.
  • ​Statement II is correct: Chronic ingestion of arsenic via groundwater heavily leads to hyperpigmentation/skin lesions and systemic peripheral vascular disease known colloquially as Black-foot disease.
  • ​Statement III is incorrect: Indoor air pollution from burning solid fuels (wood, dung, crop residues) is actually one of the leading causes of respiratory morbidity and premature death in developing nations.

​14. Consider the following statements regarding pollution indices and environmental events:

• ​Correct Answer: B) I and III only
• ​Explanation: * Statement I is correct: India's National Air Quality Index tracking monitors 8 key baseline parameters: \text{PM}_{10}, \text{PM}_{2.5}, \text{NO}_2, \text{SO}_2, \text{CO}, \text{O}_3, \text{NH}_3, and \text{Pb}.
  • ​Statement II is incorrect: India uses its own native National Air Quality Index (AQI) introduced in 2014. The Pollutant Standards Index (PSI) is an older standard framework primarily utilized in the United States and Singapore.
  • ​Statement III is correct: The Montreal Protocol signed in 1987 is universally celebrated for phasing out Chlorofluorocarbons (CFCs) to protect the stratosphere's ozone layer.

​15. Match List-I (Pollution Type) with List-II (Associated Health Hazard / Effect) and select the correct code:

• ​Correct Answer: A) i-c, ii-a, iii-d, iv-b
• ​Explanation: * Air (\text{PM}_{2.5}) deeply penetrates alveolar spaces to trigger Respiratory diseases (c).
  • ​Water (Nitrates) causes Methemoglobinemia (a) in infants.
  • ​Land (Heavy Metals) like Lead, Mercury, and Arsenic are neurotoxins causing severe Neurological disorders (d).
  • ​Noise pollution stresses auditory mechanics causing permanent or temporary Hearing loss (b).

​16. Match List-I (Environmental Agreement) with List-II (Year / Description) and select the correct code:

• ​Correct Answer: A) i-c, ii-b, iii-a, iv-d
• ​Explanation: * The Stockholm Conference in 1972 was the very first major UN conference on the human environment (c).
  • ​The Rio Summit took place in 1992, giving birth to Agenda 21 (b).
  • ​The Kyoto Protocol was adopted in 1997 establishing binding emission reduction targets (a).
  • ​The Paris Agreement was finalized in 2015 as a historic global climate pact (d).

​17. Match List-I (Resource Type) with List-II (Example) and select the correct code:

• ​Correct Answer: A) i-b, ii-a, iii-c, iv-d
• ​Explanation: * Non-renewable: Fossil fuel stocks like Petroleum (b).
  • ​Renewable: Steady infinite celestial tracking like Solar energy (a).
  • ​Abiotic: Non-living structural geography like Topography (c).
  • ​Biotic: Living biological ecosystems like a Forest (d).

​18. Match List-I (Pollution Index / Tool) with List-II (Purpose) and select the correct code:

• ​Correct Answer: A) i-c, ii-b, iii-a, iv-d
• ​Explanation: * AQI measures daily ambient Urban air quality (c).
  • ​WQI (Water Quality Index) integrates chemical assays to yield Overall water quality (b).
  • ​BOD (Biochemical Oxygen Demand) determines the degree of organic loading in water bodies, classifying Organic pollution in water (a).
  • ​PSI matches with the Old US index (d) framework.

​19. Arrange the following environmental events in chronological order (earliest first):

• ​Correct Answer: B) II-I-III-IV
• ​Explanation: * II. Stockholm Conference on Human Environment \rightarrow 1972
  • ​I. Earth Summit (Rio de Janeiro) \rightarrow 1992
  • ​III. Adoption of the Kyoto Protocol \rightarrow 1997
  • ​IV. Paris Agreement on Climate Change \rightarrow 2015

​20. Arrange the following environment-related days in chronological order within a single calendar year (earliest first):

• ​Correct Answer: A) I-III-II-IV
• ​Explanation: Looking at the standard calendar dates from January to December:
  • ​I. World Health Day \rightarrow April 7
  • ​III. Earth Day \rightarrow April 22
  • ​II. World Environment Day \rightarrow June 5
  • ​IV. World Ozone Day \rightarrow September 16

​21. The quantity of sewage generated in a town is generally estimated as approximately:

• ​Correct Answer: C) 75-85% of per-capita water supplied
• ​Explanation: In standard civil engineering practice (such as Central Public Health and Environmental Engineering Organisation standards), it is assumed that roughly 80% (or between 75% to 85%) of the domestic water consumed by a community finds its way back into the public sewer network as wastewater/sewage.

​22. For proper design of sewerage components, the design period is normally taken as:

• ​Correct Answer: C) 20-30 years for sewers and 15-25 years for treatment works
• ​Explanation: Underground sewers are capital-intensive and disruptive to replace, demanding long foresight design limits, typically 20 to 30 years. Mechanical/electrical equipment inside sewage treatment plants (STPs) wears down faster and is easier to upgrade, justifying a shorter economic design horizon of 15 to 25 years.

​23. In a conventional activated sludge process, the secondary clarifier is primarily used for:

• ​Correct Answer: B) Settling and separation of biomass (sludge) from treated effluent
• ​Explanation: The secondary clarifier sits right downstream of the aeration basin. Its explicit physical objective is to allow gravity to separate the suspended biological flocs (biomass/sludge) from the clear, stabilized supernatant fluid before final discharge.

​24. The Rotating Biological Contactor (RBC) is a type of:

• ​Correct Answer: B) Attached-growth biological system
• ​Explanation: An RBC features closely spaced circular plastic discs partially submerged in wastewater that rotate slowly. The biological slime layer (microorganisms) grows fixed directly onto the surface of these rotating discs, making it a classic fixed-film or attached-growth system.

​25. Which of the following unit operations removes fine suspended solids and colloidal particles by chemical destabilization and formation of flocs?

• ​Correct Answer: C) Coagulation and flocculation
• ​Explanation: Colloidal particles possess negative surface charges that cause them to naturally repel each other and stay suspended. Chemical coagulants neutralize these surface charges (coagulation), allowing the destabilized matter to aggregate into heavier, settleable mass when mixed slowly (flocculation).

​26. In a UASB (Upflow Anaerobic Sludge Blanket) reactor, the key feature is:

• ​Correct Answer: A) Naturally formed granular sludge bed through which wastewater flows upward
• ​Explanation: A UASB reactor is an anaerobic configuration where influent enters from the bottom and flows upward through a dense, highly active blanket of naturally aggregating granular sludge. Anaerobic digestion occurs within this dense biological bed without mechanical agitation.

​27. Which of the following industrial wastewaters is characterized by high BOD, high solids, and high alkalinity, and often requires neutralization and equalization before treatment?

• ​Correct Answer: B) Tannery
• ​Explanation: Tannery effluents are notorious for heavy, complex pollutant profiles. The unhairing, liming, and deliming processes utilize extensive volumes of calcium hydroxide and sodium sulfide, producing exceptionally high chemical alkalinity, high dissolved/suspended solids, and elevated organic loading (BOD).

​28. In a Sequencing Batch Reactor (SBR), the operational sequence within each cycle is:

• ​Correct Answer: A) Fill \rightarrow Aerate \rightarrow Settle \rightarrow Decant \rightarrow Idle
• ​Explanation: The SBR is a fill-and-draw activated sludge system where all steps occur sequentially within the same tank structure over time. The correct structural order is:
  1. ​Fill: Wastewater enters the tank.
  2. ​Aerate: Biomass consumes organic loads under aeration.
  3. ​Settle: Aeration stops, allowing sludge to settle via gravity.
  4. ​Decant: Clear treated water is skimmed/withdrawn from the top.
  5. ​Idle: The basin waits for the next incoming batch cycle.

​29. Which of the following pumps is most commonly used for pumping raw sewage containing suspended solids?

• ​Correct Answer: D) Centrifugal pump with open impeller
• ​Explanation: Raw sewage contains large solids, rags, and fibrous debris. Closed impellers would clog instantly. An open or semi-open impeller design provides wide internal clearance passages that let large objects pass through without binding the internal pump components.

​30. Pumping stations for sewage are generally located:

• ​Correct Answer: B) At depression points, along the sewer line, and at the sewage treatment plant head
• ​Explanation: Sewers operate via natural gravity flow. As a pipe travels further down a slope, it gets deeper underground. Pumping stations are strategically installed at topographic low zones (depression points) to lift the wastewater back up to shallow depths or to elevate it into the entry headworks of an STP.

​31. Consider the following statements about sewage discharge and design periods:

• ​Correct Answer: B) I and III only
• ​Explanation: * Statement I is correct: The standard design engineering translation coefficient from clean water supply to sewer discharge is roughly 75-85%.
  • ​Statement II is incorrect: Average daily flow is not sufficient for sizing all components. Lateral and branch sewers must be sized using calculated peak factors to accommodate surge hours without causing backups.
  • ​Statement III is correct: Collecting sewers are designed for longer operational lifespans (20–30 years) because replacing dug-up lines is intensely disruptive, whereas treatment plants are built for shorter timelines (15-25 years).

​32. Consider the following statements regarding unit operations in water and wastewater treatment:

• ​Correct Answer: B) I and III only
• ​Explanation: * Statement I is correct: Coagulation collapses the electrical double layer around colloids to eliminate repulsive charges, while flocculation physically bridges them together into larger flocs.
  • ​Statement II is incorrect: Sedimentation tanks rely on pure gravity settling to pull out suspended particulate solids, not dissolved organics.
  • ​Statement III is correct: Activated carbon offers massive surface area configurations ideal for adsorbing dissolved trace organics responsible for unpleasant tastes, odors, complex dyes, and micropollutants.

​33. Consider the following statements regarding biological treatment systems:

• ​Correct Answer: A) I and II only
• ​Explanation: * Statement I is correct: Wastewater trickles over rock or structured plastic media where a fixed film of biological slime grows attached, making it an attached-growth process.
  • ​Statement II is correct: SBR relies on suspended biological solids mixed through fluid agitation within a single containment vessel working across cyclic time sequences.
  • ​Statement III is incorrect: Anaerobic filters are highly effective and routinely deployed for treating high-strength industrial effluents alongside municipal sewage.

​34. Consider the following statements regarding nitrification and denitrification:

• ​Correct Answer: A) I and II only
• ​Explanation: * Statement I is correct: Nitrification is an aerobic process where specialized autotrophic bacteria convert ammonia (\text{NH}_4^+) to nitrite (\text{NO}_2^-) and then to nitrate (\text{NO}_3^-).
  • ​Statement II is correct: Denitrification occurs under anoxic/anaerobic zones where heterotrophic organisms break down nitrate (\text{NO}_3^-) to release gaseous nitrogen (\text{N}_2).
  • ​Statement III is incorrect: These two phases require completely opposite biochemical pathways and conditions executed by distinct bacterial groups (Nitrification uses obligate autotrophs like Nitrosomonas and Nitrobacter; Denitrification utilizes facultative heterotrophs like Pseudomonas).

​35. Match List-I (Unit Process) with List-II (Primary Purpose) and select the correct code:

• ​Correct Answer: A) i-b, ii-c, iii-d, iv-a
• ​Explanation: * Equalization dampens surges to achieve a Reduction of variations (b) in flow and concentration.
  • ​Aeration physically mixes ambient gas to Supply oxygen (c) to aerobic microbes.
  • ​Adsorption traps complex dissolved organics for the Removal of color/odour (d).
  • ​Disinfection targets pathogens for Pathogen removal (a).

​36. Match List-I (Biological System) with List-II (Type of Growth / Configuration) and select the correct code:

• ​Correct Answer: A) i-c, ii-b, iii-a, iv-d
• ​Explanation: * Activated Sludge uses a Suspended (aeration+clarifier) (c) configuration.
  • ​Trickling Filter uses a stationary media bed, thus classified as Attached (stationary) (b).
  • ​RBC (Rotating Biological Contactor) relies on rotating media disks, making it Attached (rotating) (a).
  • ​UASB utilizes a dense, granular anaerobic bed, linking with Anaerobic granular bed (d).

​37. Match List-I (Industrial Effluent) with List-II (Characteristics / Major Issues) and select the correct code:

• ​Correct Answer: A) i-c, ii-d, iii-b, iv-a
• ​Explanation: * Textile mills discharge huge amounts of spent Colour/Dyes (c).
  • ​Tannery processes use heavy chemical steps leaving severe Organics/Chromium (d) residues.
  • ​Dairy processing waste streams run thick with milk washings, creating a high concentration of Nutrients/Fats (b).
  • ​Distillery spent wash generates highly concentrated anaerobic streams causing severe spent wash Salinity/Anaerobic loading (a).

​38. Match List-I (Pump Type) with List-II (Typical Use) and select the correct code:

• ​Correct Answer: A) i-b, ii-a, iii-d, iv-c
• ​Explanation: * Centrifugal pumps handle bulk fluid transfers containing light solids like Raw sewage (b).
  • ​Reciprocating positive displacement pumps generate high pressure to force thick, sluggish materials like Viscous sludge (a).
  • ​Diaphragm pumps offer highly predictable, positive displacement volumes perfect for Dosing chemicals (d) like chlorine or coagulants.
  • ​Pneumatic ejectors leverage compressed air volumes for automated, Small-scale lifting (c) jobs in deep structural sumps.

​39. Arrange the following steps in a conventional biological wastewater treatment train in correct order (flow direction):

• ​Correct Answer: B) III-IV-II-I
• ​Explanation: The standard sequential configuration of an engineering treatment train follows the order of physical particle sizes:
  • ​First, raw water hits the Primary clarifier (III) to settle heavy grit and solids out.
  • ​Next, if specific advanced coagulants are added to target fine colloids, it passes through Coagulation flocculation settling (IV).
  • ​The clear liquid then moves to the biological treatment stage in the Aeration tank (II).
  • ​Finally, the generated biological mass settles out in the Secondary clarifier (I).

​40. Arrange the following biological treatment configurations in the order of increasing level of process control / sophistication (simplest first):

• ​Correct Answer: A) I-II-III-IV
• ​Explanation: * Wastewater stabilization ponds (I) are the simplest, relying entirely on natural open sunlight and ambient algae-bacteria symbiosis with no mechanical controls.
  • ​Trickling filters (II) introduce fixed passive engineering media beds but have low mechanical automation requirements.
  • ​Conventional activated sludge processes (III) require active mechanical aeration, continuous sludge recycling lines, and steady monitoring of return flows.
  • ​Sequencing Batch Reactors (SBR) (IV) are the most advanced and sophisticated, demanding highly automated, automated time-phased valve configurations and digital PLC control logic to cycle through operational steps within a single basin.

​41. Which of the following is primarily a physical characteristic of water or sewage?

• ​Correct Answer: D) Turbidity
• ​Explanation: Turbidity is an index of the light-scattering property of water caused by suspended clay, silt, and finely divided organic matter. It is a direct physical optical property. pH is a chemical parameter, while BOD and COD are chemical/biochemical measures of organic loading.

​42. High BOD in wastewater indicates:

• ​Correct Answer: B) High concentration of biodegradable organic matter
• ​Explanation: Biochemical Oxygen Demand (BOD) measures the amount of dissolved oxygen required by aerobic microorganisms to biologically decompose the organic matter present in a water sample. A higher BOD value means there is a high concentration of biodegradable organic waste utilizing that oxygen.