Environmental and Chemical Engineering (Code: 393) MCQs: Answer Key

1. The Occupational Health Services convention was held during the year:

A) 1975

B) 1985

C) 1995

D) 1997

E) Answer not known

Explanation: The Occupational Health Services Convention (C161) was adopted by the International Labour Organization (ILO) in 1985. This convention aims to establish occupational health services in workplaces.

2. Choose the right matches among type:

1. PLIBEL - Identification of Ergonomic Hazards
2. DMQ - Fire safety and rescue
3. QEC - Work place risk assessment
4. RULA - Emergence management

A) 1 and 3 are correct

B) 1 and 2 are correct

C) 2 and 3 are correct

D) 3 and 4 are correct

E) Answer not known

Explanation: PLIBEL is a tool for identifying ergonomic hazards and QEC (Quick Exposure Check) is used for workplace risk assessment.

3. The probability of adverse effects on human health resulting from some defined condition of exposure to a particular environmental agent or combination of agents is known as:

A) Risk

B) Hazard

C) Vulnerable

D) Threat

E) Answer not known

Explanation: Risk is the probability of adverse effects on human health from a defined exposure to an environmental agent.

4. The toxicants that damage kidney (nephrotoxics) are:

A) Lead, Chromium, Cadmium

B) Chromium, Arsenic, Mercury

C) Cadmium, Arsenic, Chromium

D) Mercury, Cadmium, Lead

E) Answer not known

Explanation: Mercury, Cadmium, and Lead are all well-known nephrotoxicants that can cause kidney damage.

5. Choose the characteristics of disasters from the following:

1. Usually occurs because of one of the danger sources
2. Seriously and substantially impact the most vulnerable groups
3. Results in serious imbalance in community functions
4. Results in significant losses in human lives, materials and environment

A) 2, 3 and 4

B) 1, 2 and 3

C) 1, 2, 3 and 4

D) 2 and 4

E) Answer not known

Explanation: Disasters are characterized by their significant impact on vulnerable populations, community functions, and resulting in substantial losses.

6. Cognitive ergonomics tool is formulated around the concepts of:

A) By ignoring fundamental principles of human actions

B) Human abnormal behaviour analysis

C) Mental work and cognitive tool

D) Problems of design

E) Answer not known

Explanation: Cognitive ergonomics focuses on the study of mental processes like memory, reasoning, and perception in relation to human-system interaction.

7. Types of Hazards in workplace are:

1. Mechanical, vibrational and noise
2. Heat and temperature
3. Flammability
4. Pressure Hazard

A) 1, 2, 3 and 4

B) 1, 2, and 3

C) 3 and 4

D) 2 alone

E) Answer not known

Explanation: All the listed options are recognized types of hazards that can be present in a workplace environment.

8. Major Hazardous risk associated with pesticide manufacturing industries are:

A) Toxic chemical and flammable material

B) Highly reactive (or) corrosive and extreme condition of temperature

C) Large mechanical equipment pressure of collision

D) Toxic chemical and highly reactive (or) corrosive

E) Answer not known

Explanation: The primary risks in pesticide manufacturing involve the use of toxic, highly reactive, and corrosive chemicals.

9. Assertion [A]: The bill and Melinda Gates foundation has pledged $200 million for medical aid to developing countries to help fight AIDS, TB and malaria as the establishment of emergency preparedness.

Reason [R]: As a antiretroviral therapy and antibodies to combat mother to child transmission or breast breeding had proven results in AIDS control

A) Both [A] and [R] are false

B) [A] is true but [R] is false

C) [A] is false but [R] is true

D) Both [A] and [R] are true

E) Answer not known

Explanation: Both the assertion and the reason are factually correct statements.

10. Choose the right matches among gloves type:

1. Type 1 glove - 650 rms voltage
2. Type 2 glove - 1300 rms voltage
3. Type 3 glove - 3300 rms voltage
4. Type 4 glove - 6600 rms voltage

A) 1 and 3 are correct

B) 1 and 2 are correct

C) 2 and 3 are correct

D) 3 and 4 are correct

E) Answer not known

Explanation: Standard electrical gloves are rated by voltage. Type 1 is for 650 V, and Type 2 is for 1300 V.

11. Which of the following statements are true about emergency evacuation?

1. A precise estimate of the evacuation route is of primary importance to the evacuation planners.
2. Wardrop's system optimal (so) flow is best suited to decide evacuation route
3. Hope and Tardos introduced a first polynomial time algorithm for evacuation

A) (i) only

B) (i) and (iii) only

C) (i) and (ii) only

D) (ii) and (iii) only

E) Answer not known

Explanation: Statements (i) and (ii) are accurate regarding the importance of route estimation and the application of Wardrop's principle in evacuation planning. Statement (iii) is not directly related.

12. The provision of facilities to maintain the health and well-being of individuals at the work place is known as:

A) Safety

B) Protection

C) Welfare

D) Near miss

E) Answer not known

Explanation: Welfare in the workplace refers to providing facilities for the health and well-being of employees.

13. The process of characterizing the relationship between the dose of an agent received and the incidence of an adverse health effect is known as:

A) Exposure assessment

B) Risk characterization

C) Dose response assessment

D) Hazard identification

E) Answer not known

Explanation: Dose-response assessment is the process of studying the relationship between a dose and the resulting health effect.

14. Which of the following statements are correct about Electrical Equipment Safety?

1. Rubber gloves must be worn when electrician working near 'live' wires carrying 440 volts or more
2. All portable electric tools and equipment at office and laboratory equipment shall be inspected at regular intervals by an electrician
3. Two experienced men are necessary when working with 440 volts or more

A) (i) only

B) (i) and (iii) only

C) (i) and (ii) only

D) (ii) and (iii) only

E) Answer not known

E) Answer not known

Explanation: Specific rules and regulations for electrical safety vary by jurisdiction and standard. A definitive answer cannot be provided without specifying the governing body or code.

15. Which of the following is a major pollutant from E-waste?

A) Aluminum

B) Copper

C) (PBB) - Polybrominated biphenyl

D) Zinc

E) Answer not known

Explanation: Polybrominated biphenyls (PBBs) are a class of toxic pollutants often used as flame retardants in plastics found in electronic devices, making them a major pollutant from e-waste.

16. Select the correct benefits of EIA

1. Environmental condition for better design
2. It helps to reduce the project cost
3. Insures appropriate mitigation measures to be taken
4. To understand extensive ecological and socio-economic indicators.

A) b, d

B) a, b and c

C) c, d

D) b, c and d

E) Answer not known

Explanation: EIA helps in identifying mitigation measures and understanding the ecological and socio-economic impacts of a project. It does not necessarily reduce project costs.

17. Environmental clearance notification is given by:

A) Ministry of Human Resources Development

B) Ministry of Environment and Forest

C) Ministry of Health

D) Ministry of Commerce

E) Answer not known

Explanation: In India, the Ministry of Environment, Forest, and Climate Change issues environmental clearance notifications.

18. Which action involves the impact linkages between the natural and social environment?

A) Impact Prediction and Assessment

B) Cumulative Impacts

C) Direct Impacts

D) Alternate Impacts

E) Answer not known

Explanation: Impact prediction and assessment involves forecasting the effects of a project by considering the links between the natural and social environments.

19. Assertion [A]: Expert committees for environmental assessment are constituted to ensure multidisciplinary inputs for development projects.

Reason [R]: These committees cover sectors such as mining, industrial, thermal power, river valley, infrastructure and nuclear power projects.

A) Both [A] and [R] are true and [R] is the correct explanation of [A]

B) Both [A] and [R] are true, but [R] is not the correct explanation of [A]

C) [A] is true, but [R] is false

D) [A] is false, but [R] is true

E) Answer not known

Explanation: The reason correctly explains why expert committees need multidisciplinary inputs: they assess projects across various sectors that require diverse expertise.

20. Assertion [A]: The Coastal Regulation Zone (CRZ) notification, 1991, aims to promote large-scale industrial development along coastal areas.

Reason [R]: The CRZ notification is intended to ensure the conservation and proper management of coastal ecosystems through regulated activities.

A) Both [A] and [R] are true and [R] is the correct explanation of [A]

B) Both [A] and [R] are true, but [R] is not the correct explanation of [A]

C) [A] is true, but [R] is false

D) [A] is false, but [R] is true

E) Answer not known

Explanation: The assertion is false because the CRZ notification restricts industrial development. The reason is true, as the purpose of CRZ is conservation and management.

21. What is the primary purpose of project screening in the EIA process?

A) To finalize the budget for environmental mitigation measures

B) To identify whether a proposed project requires EIA

C) To approve the project location

D) To determine the post-construction environmental audit requirements

E) Answer not known

Explanation: The purpose of screening is to determine if a project's potential environmental effects are significant enough to warrant an Environmental Impact Assessment.

22. Among the following, identify the criteria which is responsible to satisfy the objective of National Environment Policy such as conservation of critical Environmental resources:

A) Time and costs

B) Projects for economic and social development

C) Conservation of invaluable natural and manmade heritage

D) Academic and Research Community

E) Answer not known

Explanation: Conservation of invaluable natural and man-made heritage is a core objective of a national environmental policy aimed at protecting critical resources.

23. The Environment Protection Act, 1986 requires ____ and is to be submitted to State Pollution Control Board.

A) To disclose their discharge level

B) Prohibition to discharge of pollutings matter

C) Environmental Audit

D) Community reserves

E) Answer not known

Explanation: The Environment Protection Act, 1986, mandates that industries submit an Environmental Audit to the State Pollution Control Board.

24. Which substance was added to the list of controlled substances in the Kigali Amendment to the Montreal protocol?

A) Carbon dioxide

B) Hydro fluoro Carbons (HFCs)

C) Methane

D) Nitrogen

E) Answer not known

Explanation: The Kigali Amendment, which came into effect in 2019, specifically added Hydrofluorocarbons (HFCs) to the list of controlled substances under the Montreal Protocol.

25. What is the first stage of the environmental clearance process for site-specific projects like mining, river valley, ports and harbours?

A) Environmental clearance

B) Final Approval from the State Government

C) Site Clearance

D) Construction permit

E) Answer not known

Explanation: For site-specific projects, the initial stage of the environmental clearance process is to obtain a "Site Clearance."

26. Assertion [A]: The Environment Protection Act, 1986 integrates various environmental laws, providing a unified approach to environmental protection and pollution control.

Reason [R]: The Act was enacted in response to the Bhopal Gas Tragedy to fill gaps in existing environmental regulations.

A) Both [A] and [R] are true and [R] is the correct explanation of [A]

B) Both [A] and [R] are true, but [R] is not the correct explanation of [A]

C) [A] is true, but [R] is false

D) [A] is false, but [R] is true

E) Answer not known

Explanation: The Act was a direct response to the Bhopal Gas Tragedy, which highlighted the need for a comprehensive legal framework for environmental protection, thereby making the reason a correct explanation for the assertion.

27. Assertion [A]: The Air (Prevention and Control of Pollution) Act, 1981 aims to Prevent, Control and abate air pollution in India.

Reason [R]: The Act was primarily enacted to regulate forest conservation and wildlife protection.

A) Both [A] and [R] are true and [R] is the correct explanation of [A]

B) Both [A] and [R] are true, but [R] is not the correct explanation of [A]

C) [A] is true, but [R] is false

D) [A] is false, but [R] is true

E) Answer not known

Explanation: The assertion is correct regarding the purpose of the Air Act. However, the reason is false, as forest and wildlife protection are covered by separate legislation.

28. Assertion [A]: The 24-hour $NO_{2}$ concentration standard under the NAAQS is the same for industrial and ecologically sensitive areas.

Reason [R]: $NO_{2}$ has similar harmful effects in all areas, irrespective of ecological sensitivity.

A) Both [A] and [R] are true and [R] is the correct explanation of [A]

B) Both [A] and [R] are true, but [R] is not the correct explanation of [A]

C) [A] is true, but [R] is false

D) [A] is false, but [R] is true

E) Answer not known

Explanation: The National Ambient Air Quality Standards (NAAQS) have different concentration standards for industrial, residential, and ecologically sensitive areas, making the assertion false.

29. According to the Water Act, 1974, which of the following is not a power granted to the Central Pollution Control Board (CPCB)?

A) To plan nation wide programs for the prevention and control of water pollution

B) To advise the Central Government on matters related to water pollution

C) To levy and collect water cess from industries

D) To coordinate activities of State Pollution Control Boards

E) Answer not known

Explanation: The power to levy and collect water cess is granted under the Water (Prevention and Control of Pollution) Cess Act of 1977, not the Water Act of 1974.

30. Assertion [A]: The 24-hour PM2.5 standard allows exceedance only up to three times a year.

Reason [R]: PM2.5 particles can penetrate deep into the lungs and cause severe health issues, so strict limits are necessary.

A) Both [A] and [R] are true and [R] is the correct explanation of [A]

B) Both [A] and [R] are true, but [R] is not the correct explanation of [A]

C) [A] is true, but [R] is false

D) [A] is false, but [R] is true

E) Answer not known

Explanation: The assertion regarding the number of allowed exceedances is incorrect. While the reason about the health effects of PM2.5 is true, it does not correctly explain the false assertion.

31. Assertion [A]: The Water Cess Act, 1977 was last amended in 2003 to improve compliance and administration.

Reason [R]: The amendment removed the requirements for industries to maintain water consumption records.

A) Both [A] and [R] are true and [R] is the correct explanation of [A]

B) Both [A] and [R] are true, but [R] is not the correct explanation of [A]

C) [A] is true, but [R] is false

D) [A] is false, but [R] is true

E) Answer not known

Explanation: The assertion that the Act was amended in 2003 is true. However, the reason is false because the amendment actually strengthened, not removed, the requirements for maintaining water consumption records.

32. For which of the following violating the provision of the Water Act will impose penaling?

1. Failure to provide information about discharging effluents.
2. For prohibiting discharge of any polluting matter into stream.
3. Discharging coloured effluent to environment.
4. For prohibiting discharge of solid wastes.

A) (i) and (ii)

B) (iii) and (iv)

C) (ii), (iii) and (iv)

D) (i), (ii) and (iv)

E) Answer not known

Explanation: The Water Act provides for penalties for failing to provide information on effluents, discharging polluting matter into streams, and discharging solid wastes. Discharging coloured effluent is a specific example of discharging polluting matter, which is covered by (ii).

33. The notification amended to obtain environmental clearance for development projects come under:

A) Disposal of fly ash notification

B) Coastal Regulation notification

C) Doon valley notification

D) Environmental Impact Assessment notification

E) Answer not known

Explanation: The Environmental Impact Assessment (EIA) notification is the legal instrument that governs the process of obtaining environmental clearance for development projects in India.

34. Assertion [A]: Producers have the obligation of Extended Producer Responsibility (EPR) to meet recycling or refurbishing targets for batteries they introduce into the market.

Reason [R]: EPR ensures producers are responsible for the entire lifecycle of the batteries, including end-of-life management.

A) Both [A] and [R] are true and [R] is the correct explanation of [A]

B) Both [A] and [R] are true, but [R] is not the correct explanation of [A]

C) [A] is true, but [R] is false

D) [A] is false, but [R] is true

E) Answer not known

Explanation: The core principle of EPR is to hold producers responsible for their products' entire lifecycle, including waste management, which is a direct reason why they are obligated to meet recycling targets.

35. Assertion [A]: Local bodies are responsible for the collection, treatment and disposal of Solid Waste Management Rules, 2016. Reason [R]: The rules assign the task of monitoring and authorizing waste management process to local bodies.

A) Both [A] and [R] are true and [R] is the correct explanation of [A]

B) Both [A] and [R] are true, but [R] is not the correct explanation of [A]

C) [A] is true, but [R] is false

D) [A] is false, but [R] is true

E) Answer not known

Explanation: The rules assign the responsibility for managing solid waste to local bodies, which is a direct reason for their accountability in collection, treatment, and disposal.

36. As per Solid Waste Management Rules, 2016, which of the following is not included in the definition of solid waste?

A) Street Sweepings

B) E-Waste

C) Horticulture Waste

D) Market Waste

E) Answer not known

Explanation: E-waste is managed under separate rules (E-Waste (Management) Rules, 2022) and is explicitly excluded from the definition of solid waste under the Solid Waste Management Rules, 2016.

37. Which of the following items was included in the ban under the Plastic Waste Management (Amendment) Rules, 2021 from 01.07.2022?

A) Plastic carry bags below 120 microns

B) Ear buds with plastic sticks

C) PVC banners above 100 microns

D) Non-woven plastic bags above 60 GSM

E) Answer not known

Explanation: The Plastic Waste Management (Amendment) Rules, 2021, banned specific single-use plastic items from July 1, 2022, including ear buds with plastic sticks.

38. What is a key objective of the E-Waste (Management) Rules, 2022?

A) Promote open dumping of e-waste

B) Ban all forms of electronics manufacturing

C) Promote Circular Economy through Extended producer Responsibility

D) Limit the role of producers in post-consumer waste management

E) Answer not known

Explanation: The E-Waste (Management) Rules, 2022, aim to promote a circular economy by strengthening the principle of Extended Producer Responsibility (EPR).

39. Which of the following is an essential element of (Integrated Solid Waste Management) ISWM for achieving sustainability?

A) Emphasis on disposal and incineration

B) Focus on resource recovery and minimizing waste generation

C) Focus only on waste collection

D) Ignoring recycling and focusing only on treatment

E) Answer not known

Explanation: Integrated Solid Waste Management prioritizes a hierarchy of waste management strategies, with a strong emphasis on resource recovery and waste minimization at the source to achieve sustainability.

40. Why does waste generation tend to be higher in urban areas than in rural areas?

A) Urban areas use more natural fertilizers

B) Urban lifestyles involve more consumption and packaging

C) Rural areas generate more hazardous waste

D) Urban areas have fewer people

E) Answer not known

Explanation: The higher density of population and consumer-oriented lifestyles in urban areas lead to greater consumption of goods and products with more packaging, resulting in higher waste generation.

41. Among the following choose the best/correct methods with correct options (both) used to removing submicron particulates of size 0.5 µm to 1 µm from polluted air:

1. venturi scrubber
2. spray tower
3. fabric filters
4. gravitational settling chambers

A) (1) and (3)

B) (2) and (3)

C) (2) and (4)

D) (1) and (4)

E) Answer not known

Explanation: Venturi scrubbers and fabric filters are highly effective at removing small particles, including those in the sub-micron range, from polluted air.

42. Organic solvent vapours are adsorbed from the gaseous pollutants using which of the following?

A) Iron oxide

B) Alkaline allumina

C) Bauxite

D) Activated carbon

E) Answer not known

Explanation: Activated carbon has a high surface area and is widely used for the adsorption of organic vapors from gas streams.

43. Acceptable indoor noise level for Radio and TV studios is:

A) 30-35 dB (A)

B) 40-45 dB (A)

C) 25-30 dB (A)

D) 25-35 dB (A)

E) Answer not known

Explanation: Radio and TV studios require a very low ambient noise level to ensure high-quality recordings, typically in the range of 25-30 dB(A).

44. The maximum permissible standards of sulphur di oxide for residential area in the New Revised National Ambient Air Qualities Standards in India is:

A) $30~\mu g/m^{3}$

B) $120~\mu g/m^{3}$

C) $50~\mu g/m^{3}$

D) $60~\mu g/m^{3}$

E) Answer not known

Explanation: As per the New Revised National Ambient Air Quality Standards (NAAQS) in India, the annual average standard for $SO_{2}$ in residential areas is $60~\mu g/m^{3}$. The 24-hour standard is $80~\mu g/m^{3}$.

45. Which of the following involves forcing or pumping in fresh air, and causing the vitiated air to be exhausted out either by itself or through an exhaust fan placed at the outlet?

A) Vaccum system

B) Plenum system

C) Air conditioning system

D) Air cooler system

E) Answer not known

Explanation: A plenum system is a type of ventilation system that uses positive pressure to force fresh air into a space, which in turn pushes out the vitiated air.

46. How much is the noise standard for passenger cars as per Environment (Protection) Rules 1986 in dB(A)?

A) 82

B) 85

C) 89

D) 75

E) Answer not known

Explanation: The noise standard for passenger cars as per the Environment (Protection) Rules 1986 in India is 82 dB(A), with a tolerance of 3 dB(A), making 85 dB(A) the permissible upper limit.

47. Which of the following is responsible for changing oligotrophic water into intensity protective eutrophic water in fresh and marine eco systems?

A) Calcium and phosphate nutrient species

B) Potassium and phosphorus nutrient species

C) Nitrogen and phosphorus nutrient species

D) Chloride and sodium nutrient species

E) Answer not known

Explanation: Eutrophication is the process caused by an over-enrichment of nutrients, primarily nitrogen and phosphorus, which leads to excessive algal growth in water bodies.

48. The Montreal protocol is aimed to phase out the production of:

A) $SO_{2}$

B) $NO_{2}$

C) $VOC_{S}$

D) $CFC_{S}$

E) Answer not known

Explanation: The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production and consumption of ozone-depleting substances, such as chlorofluorocarbons (CFCs).

49. The cleaning capability of cyclonic scrubber wet collectors is about:

A) 2500 litres of gas/per minute

B) 2000 litres of gas/per minute

C) 1500 litres of gas/per minute

D) 2250 litres of gas/per minute

E) Answer not known

Explanation: The cleaning capability of cyclonic scrubbers is highly dependent on their design and the type of particles being removed. A single fixed value is not appropriate.

50. A organic carcinogenic compound present in cigarette smoke is:

A) Carbondioxide

B) Sulphurdioxide

C) Benzo (a) pyrene

D) Benzy azo Nitrine

E) Answer not known

Explanation: Benzo(a)pyrene is a well-known polycyclic aromatic hydrocarbon (PAH) and a potent carcinogen found in cigarette smoke.

51. Choose the right answer among type of sources in connection with Air Pollution.

1. Solid waste disposal is area source
2. Power plants are point source
3. Onsite incineration is point source
4. Railyard locomotives is area source

A) (1) and (3) are correct

B) (2) and (3) are correct

C) (2) and (4) are correct

D) (3) and (4) are correct

E) Answer not known

Explanation: Point sources are single, identifiable sources of pollution like power plants and on-site incinerators. Solid waste disposal and railyard locomotives are typically classified as area sources.

52. Petrol engine receive ____ than Diesel engine.

A) High fuel content mixture

B) Low fuel content mixture

C) Moderate fuel content mixture

D) Equal fuel content mixture

E) Answer not known

Explanation: Petrol engines operate with a relatively richer air-fuel mixture (high fuel content mixture) compared to diesel engines, which use a lean mixture.

53. Fluidised bed combustion (FBC) is one of the modified and New type of combustion chamber because:

1. It increase the coal combustion and decrease the heat transfer.
2. It reduce the coal combustion as well as decrease the heat transfer.
3. It increase the coal combustion efficiency
4. It increase the efficiency of coal combustion as well as heat transfer

A) (iv) only

B) (ii) only

C) (iii) and (ii)

D) (i) only

E) Answer not known

Explanation: Fluidized bed combustion is an advanced technology that increases the efficiency of coal combustion as well as heat transfer.

54. 'London Smog' occurred in:

A) December 1952

B) November 1952

C) December 1954

D) October 1952

E) Answer not known

Explanation: The Great Smog of London, a severe air pollution event, occurred from December 5th to December 9th, 1952.

55. Exposure to $NO_{2}$ even in a small concentration but longer period leads to:

A) Lungs problem

B) Liver problem

C) Kidneys problem

D) Heart problem

E) Answer not known

Explanation: Nitrogen dioxide ($NO_{2}$) is a respiratory irritant and long-term exposure can lead to chronic lung problems and an increased susceptibility to respiratory infections.

56. Which of the following models is primarily used for evaluating the impact of air quality management practices for multiple pollutants at multiple scales?

A) CAMX

B) CMAQ

C) UAM

D) CALGRID

E) Answer not known

Explanation: CMAQ (Community Multiscale Air Quality) is a complex and widely used model for evaluating air quality management practices for multiple pollutants at various scales.

57. What does the dispersion model describe?

A) The rate of pollutant emission overtime

B) How pollutants or particles spread in the environment

C) The temperature changes in a given area

D) The chemical reaction rate of pollutants

E) Answer not known

Explanation: A dispersion model is a mathematical simulation used to predict how pollutants or other substances move and spread through the atmosphere, water, or soil.

58. Which of the following field tests is typically used in transient simulations?

A) grain size analysis

B) slug test

C) isotope tracing

D) soil classification

E) Answer not known

Explanation: A slug test is a field test used to determine the hydraulic properties of an aquifer by observing its response to an instantaneous change in water level, which is a transient simulation.

59. Assertion [A]: Bubble aeration is a process where gas transfer occurs across the gas water interface of gas bubbles, which is commonly used in activated sludge systems. Reasons [R]: According to Bewtra (1962), Oxygen transfer from bubbles occurs in three phases: formation of the bubble at the capillary opening, bubble.

A) Both [A] and [R] are correct and the [R] is the correct explanation for the [A]

B) Both [A] and [R] are correct, but the [R] is not the correct explanation for [A]

C) [A] is correct, but the [R] is incorrect

D) [A] is incorrect, but the [R] is correct

E) Answer not known

Explanation: The reason provided is incomplete, making it impossible to determine if it is a correct explanation for the assertion.

60. In the Oxygen sag curve model of a stream receiving organic waste, the lowest point of dissolved oxygen typically occurs in:

A) zone of degradation

B) zone of active decomposition

C) zone of recovery

D) zone of clean water

E) Answer not known

Explanation: The lowest point of dissolved oxygen, or the sag point, occurs in the zone of active decomposition where the rate of oxygen consumption by microorganisms is at its maximum.

61. The greater the number and diversity of confirming observations, the more probable it is that the conceptualization embodied in the model is not flawed such a model is said to be:

A) Weak

B) Robust

C) Adequate

D) Frail

E) Answer not known

Explanation: A robust model is one that performs reliably under a wide range of conditions and with diverse data, confirming its underlying principles.

62. Standard deviation of sampling distribution of mean is (Notations are as usual):

A) $\frac{\sigma}{n}$

B) $\sigma/\sqrt{n}$

C) $\frac{\sigma}{n^{2}}$

D) $\sqrt{\sigma/n}$

E) Answer not known

Explanation: The standard deviation of the sampling distribution of the mean is also known as the standard error of the mean. Its formula is $\frac{\sigma}{\sqrt{n}}$, where $\sigma$ is the population standard deviation and n is the sample size.

63. In stratified sampling, the population is divided into:

A) Groups with equal sizes

B) Homogenous sub groups

C) Randomly selected groups

D) Heterogeneous clusters

E) Answer not known

Explanation: Stratified sampling divides a population into homogeneous subgroups (strata) before sampling from each.

64. What does the theory of testing of hypothesis employ to make decisions?

A) Large population data

B) Sample theory and statistical techniques

C) Experimental design only

D) Visual data representation

E) Answer not known

Explanation: Hypothesis testing uses statistical methods on sample data to make inferences about a larger population.

65. In which of the following situations a test of significance is NOT typically applied?

A) Testing if a machine fills exactly 500 ml of milk

B) Comparing the productivity of two manufacturing processes

C) Calculating mean rainfall for the last 10 years

D) Checking if students IQ scores meet a standard

E) Answer not known

Explanation: A test of significance is for making inferences about a population from a sample. Calculating a descriptive statistic like the mean of a known historical dataset does not require it.

66. A study claims that forest fires in Uttarakhand have increased by 13% which of the following represents the most appropriate null and alternative hypothesis?

A) $H_{o}$: Increase in less than 13%, Ha: Increase is 13%

B) $H_{o}$: Increase exactly 13%, Ha: Increase is not 13%

C) $H_{o}$: Increase is more than 13%, Ha: Increase is 13%

D) $H_{o}$: No increase, Ha: Increase is exactly 13%

E) Answer not known

Explanation: The null hypothesis ($H_{o}$) is the statement being tested, while the alternative hypothesis ($H_{a}$) is what is concluded if the null hypothesis is rejected.

67. The analysis in which the model is used to inspect the system and gain insight into how the system works. This analysis is:

A) Exploratory analysis

B) Case analysis

C) Model validation analysis

D) Problem definition

E) Answer not known

Explanation: Exploratory analysis is used to understand the characteristics of a system and its underlying data, often without a predefined hypothesis.

68. Assertion (A): In modelling, a variable is a value that changes freely in time and space. Reason (R): A State variable represents a State or compartment in the model.

A) Both [A] and [R] is true and [R] is the correct explanation of [A]

B) Both [A] and [R] is true but [R] is not the correct explanation of [A]

C) [A] is true, but [R] is false

D) [A] is false but [R] is true

E) Answer not known

Explanation: The definition of a variable and a state variable are both correct, and the reason for the variable's free change (A) is its role in representing a state (R).

69. Which of the following error/errors arise during the computer representation of the algorithm that operationalises the model?

A) Computational errors

B) Procedural errors

C) Propagation errors

D) Both (A) and (B)

E) Answer not known

Explanation: Computational errors arise from numerical issues when a computer performs calculations, such as rounding or truncation errors in the algorithm's representation.

70. Why is soil depth considered a critical factor in Environmental modeling?

A) It affects air quality and pollution level

B) It controls water flow into and through the soil

C) It increases the soil temperature

D) It limits the number of soil organisms

E) Answer not known

Explanation: Soil depth is crucial for modeling water flow into and through the soil, including infiltration and groundwater recharge, and for the transport of pollutants.

71. Rotating biological contractor treatment system is:

A) An attached growth process

B) A suspended growth process

C) A combination of attached and suspended growth process

D) Neither attached not suspended growth process

E) Answer not known

Explanation: A Rotating Biological Contactor (RBC) is a wastewater treatment system where microorganisms grow on a fixed media (discs) that are partially submerged and rotated, classifying it as an attached growth process.

72. In sludge processing, following treatments are to be done.

1. Conditioning
2. Dewatering
3. Thickening
4. Digestion
5. Disposal

Choose the correct sequences to be followed:

A) (1)→(2)→(3)→(4)→(5)

B) (2)→(1)→(3)→(4)→(5)

C) (3)→(4)→(1)→(2)→(5)

D) (4)→(1)→(2)→(3)→(5)

E) Answer not known

Explanation: The correct sequence for sludge processing is: Thickening (3), Digestion (4), Conditioning (1), Dewatering (2), and finally Disposal (5).

73. Which gas consumes more alkalinity in an anaerobic digester during anaerobic digestion process?

A) Carbon di oxide

B) Methane

C) Oxygen

D) Ammonia

E) Answer not known

Explanation: Carbon dioxide ($CO_{2}$) is produced during anaerobic digestion and reacts with water to form carbonic acid, which consumes alkalinity and can lower the pH of the digester.

74. When the recirculation ratio in a high rate trickling filter is unity, then the recirculation factor is:

A) 1

B) > 1

C) <1

D) Zero

E) Answer not known

Explanation: The recirculation factor (F) for a trickling filter with a recirculation ratio (r) of unity is calculated using a standard formula, resulting in a value of 1.25, which is greater than 1.

75. Consider the following sequence of operations in of upflow anaerobic sludge blanket reactor units for municipal sewage water treatment. Arrange the steps in the correct order:

1. Pumping → Screening → Degritting
2. Sludge blanket settling → Drying → Gas collection
3. Sludge blanket settling → Gas collection → Drying
4. Degritting → Pumping → Screening

Among the above four sequences which two are correct other two sequences are Incorrect

A) (i), (ii) are correct, (iii) and (iv) are incorrect

B) (i), (iv) are correct, (ii) and (iii) are incorrect

C) (ii), (iii) are correct, (i) and (iv) are incorrect

D) (i), (iii) are correct, (ii) and (iv) are incorrect

E) Answer not known

Explanation: The correct sequence of operations is (i) Pumping, Screening, and Degritting for primary treatment. For the anaerobic digestion process, the correct sequence is (iii) Sludge blanket settling, Gas collection, and then Drying.

76. Biological sludge does not settles and leaves a small amount of clear supernatant at the top is called as:

A) Sludge Bulking

B) Sludge Filtering

C) Sludge Thickening

D) Sludge Digesting

E) Answer not known

Explanation: Sludge bulking is a condition where the sludge does not compact and settle properly, resulting in poor clarification and an increase in the volume of the sludge.

77. National Research Council has developed empirical equation for trickling performance as $VF=\frac{W}{5.08}[\frac{E_{1}}{1-E_{1}}]^{2}$ where W stand for:

A) Carbon di oxide

B) Dissolved oxygen

C) Chemical oxygen demand

D) Biological oxygen demand

E) Answer not known

Explanation: In the National Research Council (NRC) formula for trickling filter performance, the symbol 'W' represents the mass of Biological Oxygen Demand (BOD) in the influent.

78. Sequencing Batch Reactors processes majorly used in:

A) Fertilizer Industry

B) Sugar Mill Industry

C) Petroleum Industry

D) Steel Industry

E) Answer not known

Explanation: Sequencing Batch Reactors (SBRs) are effective in treating high-strength organic wastes, making them particularly suitable for use in industries like sugar mills.

79. Which statement best distinguishes the performance of activated sludge process from Trickly filter in Municipal waste water treatment?

A) Activated sludge process uses less energy and produces less sludge than Tricky Filter

B) Trickling Filter removes nutrients better due to longer biomass retention

C) Activated sludge process handles shock loads better due to active Biomass control

D) Tricky Filter achieves better effluent quality due to diverse biofilms

E) Answer not known

Explanation: The activated sludge process, with its ability to control the biomass concentration and sludge return, provides greater operational flexibility and is better at handling variable shock loads compared to a fixed-film trickling filter.

80. Unless the sludge age in a reactor is greater than cell doubling time, the cell may get washed out of system. Thus relation between sludge age ($\theta_{c}$) and growth rate (µ) of microorganism is:

Α) $\mu\theta_{c}=1$

Β) $\mu+\theta_{c}=1$

C) $\mu-\theta_{c}=1$

D) $\mu/\theta_{c}=1$

E) Answer not known

Explanation: The relationship between the specific growth rate ($\mu$) and sludge age ($\theta_{c}$) in a chemostat reactor is given by the equation $\mu\theta_{c}=1$. This relationship is critical to avoid washout of the microbial population.

81. Which one of the following pollutants is showing resistant to microbial degradation?

A) Aliphatic derivatives

B) Carbohydrates

C) Proteins

D) Aromatic derivatives

E) Answer not known

Explanation: Aromatic derivatives, particularly those with complex ring structures, are generally more resistant to microbial degradation compared to simpler organic compounds.

82. Among the following types of aerators used in biological wastewater treatment process, which of the following aerators is not mechanical type aerator?

A) Fine bubble aerator

B) Vertical axis aerator

C) Aspirator type aerator

D) Cage rotors and brushes

E) Answer not known

Explanation: Fine bubble aerators are non-mechanical diffusers that introduce air into the wastewater to provide oxygen for microorganisms. The other options are mechanical aerators that agitate the water.

83. In membrane process water treatment, the contaminants- suspended solids, emulsified components, bacteria and protozoa are removed by:

A) Ultrafiltration

B) Nanofiltration

C) Hyperfiltration

D) Microfiltration

E) Answer not known

Explanation: Microfiltration uses membranes with larger pores to remove suspended solids, bacteria, and other large particles, but not dissolved salts or smaller viruses.

84. Consider the statements about Aerated lagoons

1. recommended for complete aerobic biological treatment of raw waste water
2. have simple holding basins usually 2-4 m deep
3. need continuous, supply of oxygen
4. need not involve with microorganisms

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

B) (i), (ii) and (iii)

C) (iv) only

D) (i), (ii) and (iv)

E) Answer not known

Explanation: Aerated lagoons use microorganisms for biological treatment, so statement (iv) is incorrect. The other statements are correct characteristics of aerated lagoons.

85. The secondary settling tank serves the following functions.

1. Clarification of liquid overflow
2. Thickening of the sludge underflow
3. Bulking of sludge by growth of filamentous microbes

A) (i) and (ii) are correct, (iii) is incorrect

B) (i) and (iii) are correct, (ii) is incorrect

C) (ii) and (iii) are correct, (i) is incorrect

D) (i) is correct, (ii) and (iii) are incorrect

E) Answer not known

Explanation: Secondary settling tanks clarify the effluent and thicken the sludge. Sludge bulking is a problem that impairs settling, not a function of the tank.

86. The secondary settling Tanks in trickling filters primarily produces:

A) Solid Effluent

B) Sludge

C) Clear effluent and biomass sludge

D) Concentrated substrate solids

E) Answer not known

Explanation: The purpose of a secondary settling tank following a trickling filter is to separate the biomass (sludge) that sloughs off the filter media, producing a clear effluent and a biomass sludge.

87. Assertion [A]: Increasing the $\frac{Qr}{Q}$ ratio indefinitely in an activated sludge process always improves treatment efficiency by maintaining hyper biomass concentrations.

Reason [R]: Higher return activated sludge flow recycles more micro organisms thus increasing the biomass retention time and improving substrate degradation.

A) Both [A] and [R] are true and [R] correctly explains [A].

B) Both [A] and [R] are true, but [R] does not correctly explains [A].

C) [A] is false, but [R] is true.

D) Both [A] and [R] are false.

E) Answer not known

Explanation: The assertion is false because there is an optimal recirculation ratio; increasing it indefinitely can lead to problems. The reason is a correct statement about the effect of higher return activated sludge flow.

88. Choose the principal approaches to process control so as to maintain high levels of treatment performance with the activated - sludge process under a wide range of operating conditions.

1. Organics that escaped biological treatment
2. Controlling the waste activated sludge
3. Not maintaining dissolved oxygen levels in aeration tanks
4. Regulating the amount of return activated sludge

A) (2) and (3) are correct

B) (1) and (4) are correct

C) (4) and (2) are correct

D) (3) and (1) are correct

E) Answer not known

Explanation: The main control strategies in the activated sludge process are managing the amount of waste activated sludge and regulating the return activated sludge to maintain the desired microorganism concentration.

89. Among the below statement which one is wrong assumption?

A) Liquid waste flow into reactor at a constant rate Q

B) They mixed instantaneously and homogeneously with the contents of the reactor

C) The mixed liquor is withdrawn at a rate not equal to the rate of inflow Q

D) Influent does not contain any active microbes

E) Answer not known

Explanation: For a continuous flow reactor, it is assumed that the inflow rate (Q) is equal to the outflow rate, ensuring a constant volume in the reactor. Therefore, the statement that the outflow rate is not equal to the inflow rate is a wrong assumption.

90. Aerobic suspended growth process used in mechanised plants are:

1. Activated sludge
2. Aerated lagoons
3. Waste sterilization ponds
4. UASB

Which one is Irrelevant?

A) (ii)

B) (iv)

C) (iii)

D) (i)

E) Answer not known

Explanation: UASB (Upflow Anaerobic Sludge Blanket) is an anaerobic process, while the other options are aerobic suspended growth processes.

91. Microorganisms are NOT categorized in which of the following ways?

A) By Phylum

B) By Carbon Source

C) By Electron Acceptor type

D) By Phyto Chemical

E) Answer not known

Explanation: Microorganisms are classified based on their phylum, carbon source, and electron acceptor type, but not by phytochemicals, which are compounds from plants.

92. Reactor design in wastewater treatment typically requires knowledge from all of the following fields except:

A) Thermodynamics

B) Fluid Mechanics

C) Microeconomics

D) Heat and Mass transfer

E) Answer not known

Explanation: While microeconomics is relevant for the financial feasibility of a project, it is not a fundamental engineering field required for the technical design of a reactor.

93. Which of the following is a key characteristic of a batch reactor in biological wastewater treatment?

A) Continuous inflow and outflow of wastewater

B) Constant biomass concentration due to sludge recycling

C) No inflow or outflow during the reaction phase

D) Biomass grows on attached media surfaces only

E) Answer not known

Explanation: A batch reactor is a closed system where reactants are added at the start, and there is no inflow or outflow during the reaction phase.

94. In an Aerated lagoon the top layer often has high pH and Oxygen levels, volatilisation from the surface can cause odour problems due to which of the following?

A) In organic acids

B) Organic acid

C) Heavy metals

D) Microbial load

E) Answer not known

Explanation: The high pH in the top layer of an aerated lagoon can lead to the volatilization of organic acids and other volatile organic compounds, causing odors.

95. Arrange the following microbial growth phases in the correct sequential order:

1. Exponential growth phase
2. Endogenous growth phase
3. Retarded growth phase

A) (c)→(a) → (b)

B) (a)→(b) → (c)

C) (b)→(a) → (c)

D) (c)→(b) → (a)

E) Answer not known

Explanation: The correct order of the listed phases is: Exponential growth (a), Retarded growth (c), and Endogenous growth (b).

96. American architect "Paul Soleri" proposed a new concept of "Ecological Architecture" in the year:

A) 1950

B) 1956

C) 1960

D) 1966

E) Answer not known

Explanation: Paolo Soleri coined the term "Arcology" (Ecological Architecture) and developed the concept in the 1960s.

97. LEED: Leadership in Energy and Environmental Design was developed in United States of America in the year:

A) 1996

B) 1997

C) 1998

D) 1999

E) Answer not known

Explanation: The LEED green building rating system was officially launched by the U.S. Green Building Council (USGBC) in 1999.

98. The U.S. Environmental Protection Agency (EPA) impact analysis estimated annual costs for existing source to be ____ million.

A) $ 20.83

B) $ 19.12

C) $ 21.73

D) None of the above

E) Answer not known

Explanation: This question refers to a specific, and likely outdated, EPA analysis. The value is not a general or universally known figure.

99. The "Nature Conservancy" was born of an older organisation called Ecologist Union on:

A) June, 5th 1960

B) October, 10th 2010

C) September, 11th 1950

D) None of the above

E) Answer not known

Explanation: The Nature Conservancy was founded on September 11, 1950, after evolving from the Ecologists Union.

100. Green buildings are designed to reduce the overall impact on:

A) Land Resources

B) Water Potential

C) Human health and natural environment

D) Economic trade

E) Answer not known

Explanation: The fundamental goal of green building design is to minimize the negative impact of construction and operation on both human health and the natural environment.

101. Emission trading, as set out in Article 17 of the:

A) Montreal protocol

B) Kyoto protocol

C) Earth summit 1972

D) None of the above

E) Answer not known

Explanation: Emission trading is a key mechanism established under Article 17 of the Kyoto Protocol to address climate change.

102. USGBC stands for:

A) U.S. Government Bank Council

B) United Nations Governing Committee

C) U.S. Green Building Council

D) U.S. Governing Building Committee

E) Answer not known

Explanation: USGBC is the acronym for the U.S. Green Building Council, the organization that developed the LEED green building certification program.

103. Which of the following is used for green building certification in India?

A) IGBC

B) GBI

C) GBCI

D) ICGB

E) Answer not known

Explanation: The Indian Green Building Council (IGBC) provides the green building certification widely used in India.

104. In the context of environmental auditing, "non-conformance" refers to:

A) A legal violation

B) A financial loss

C) A marketing failure

D) A deviation from established environmental policies or standards

E) Answer not known

Explanation: Non-conformance is a term used in auditing to describe a failure to meet a specific requirement of a policy, procedure, or standard.

105. ISO : International Organisation for Standardization (ISO) commitment was enabled for Life Cycle Assessment (LCA) in the year ____ enforcing guidelines.

A) 1960

B) 1970

C) 1994

D) 1999

E) Answer not known

Explanation: The International Organization for Standardization (ISO) began its work on a standard for Life Cycle Assessment (LCA) in 1994, leading to the development of the ISO 14040 series.

106. Which country introduced eco-labelling first in the year 1978?

A) Germany

B) USA

C) UK

D) Japan

E) Answer not known

Explanation: Germany was the first country to introduce a national eco-labelling scheme, the Blue Angel, in 1978.

107. The scheme of eco-labelling was introduced by the Ministry of Environment and Forests in the year:

A) 1991

B) 1996

C) 1992

D) 1990

E) Answer not known

Explanation: The Ecomark scheme in India, which is an eco-labelling program, was launched by the Ministry of Environment and Forests in 1991.

108. ____ is a voluntary International Standard for Environmental Management Systems (EMS).

A) ISO 14001

B) ISO 11002

C) ISO 12202

D) ISO 2020

E) Answer not known

Explanation: ISO 14001 is the globally recognized standard for Environmental Management Systems (EMS).

109. Which of the following is not true when it comes to "Ecolabelling"?

A) It identifies overall environmental preference of a product

B) It is a self-styled environmental symbol

C) It is awarded by impartial third party to products

D) It refers to provision of information to consumers about relative environmental quality of a product

E) Answer not known

Explanation: Ecolabels are awarded by independent third-party organizations, not self-declared by manufacturers.

110. ISO 26000 is the recognized standard for:

A) Corporate Social Responsibility (CSR)

B) Council for Scientific Research

C) Common Science Research Board

D) Committee on Social Response

E) Answer not known

Explanation: ISO 26000 provides guidance and recommendations for social responsibility, including Corporate Social Responsibility (CSR).

111. Which of the following country has been invited to open talks on joining OECD?

A) India

B) Israel

C) Brazil

D) China

E) Answer not known

Explanation: Israel was invited to join the OECD, along with Chile, Estonia, Russia, and Slovenia in 2007. Israel officially became a member in 2010.

112. Which SDG emphasizes healthy lives and promoting well-being for all ages?

A) Quality education

B) Good health and well being

C) Gender equality

D) Life on land

E) Answer not known

Explanation: The third Sustainable Development Goal (SDG 3) is "Good Health and Well-being," which focuses on ensuring healthy lives and promoting well-being for all ages.

113. What project helped to mainstream the concept of competencies in education policy circles?

A) UNESCO Global Schools Project

B) United Nations SDG Taskforce

C) OECD'S Definition and Selection of Competencies (DESECO)

D) International Baccalaureate initiative

E) Answer not known

Explanation: The OECD's DESECO project was influential in defining and promoting the concept of competencies in education policy on an international level.

114. Match the following type:
Match the International Convention Treaty with their respective agenda.

Convention/Treaty

1. Montreal protocol
2. Stockholm convention
3. Kyoto protocol
4. Rio-declaration

Cause/Agenda

1. Persistent organic pollutant
2. Sustainable development
3. Ozone layer
4. Green house gas emission

A) (a)-3, (b)-1, (c)-4, (d)-2

B) (a)-2, (b)-3, (c)-4, (d)-1

C) (a)-3, (b)-4, (c)-2, (d)-1

D) (a)-2, (b)-1, (c)-4, (d)-3

E) Answer not known

Explanation: Montreal Protocol deals with the ozone layer. Stockholm Convention is on Persistent Organic Pollutants. Kyoto Protocol is about greenhouse gas emissions. Rio Declaration is about sustainable development.

115. According to environmental protection agency, the clean air Act, 1970 helped to reduce emissions of which one of the following remains a more difficult to control.

A) NOx

B) Pd

C) $SO_{2}$

D) CO

E) Answer not known

Explanation: While the Clean Air Act has been effective for many pollutants, controlling nitrogen oxides (NOx) remains a significant challenge, especially from mobile sources.

116. Assertion [A] : The most significant pollutant emitted by bagasse-fired boilers is particulate matter Reason [R] : Auxilliary fuels (fuel oil or Natural gas) may be used during startup of the boiler when the moisture content of the bagasse is too high.

A) [A] is false but [R] is true

B) Both [A] and [R] are true; and [R] is the correct explanation of [A]

C) [A] is false, [R] is true

D) Both [A] and [R] are true, but [R] is not the correct explanation of [A]

E) Answer not known

Explanation: Both statements are true, but the use of auxiliary fuels is not the reason why particulate matter is the most significant pollutant.

117. On the use of paper mill wastewater for irrigation, it is observed that percolates from the field had no colour and no lignin. Which of the following (in the soil) could be attributed to the aforesaid observation?

A) Base exchange capacity

B) Acid exchange capacity

C) Presence of monovalent salts

D) Presence of magnesium ions

E) Answer not known

Explanation: The base exchange capacity of soil allows it to adsorb and retain certain organic compounds, including the colored compounds and lignin from the wastewater.

118. Identify the fungus involved in degradation of chlorinated lignin derivatives of paper industry.

A) White rot fungus

B) Red rot fungus

C) Grey mould

D) Blue mould

E) Answer not known

Explanation: White rot fungus is well-known for its ability to produce enzymes that can degrade lignin and its chlorinated derivatives, making it useful in treating paper industry waste.

119. Which type of treatment is necessary for the petrochemical industry waste water before it is subjected to biological treatment?

A) Flotation

B) Flocculation

C) Filtration

D) Oxidation

E) Answer not known

Explanation: Petrochemical wastewater often contains oil and grease, which are most effectively removed by flotation before being subjected to biological treatment.

120. Assertion [A]: Mechanical collectors and wet scrubbers are commonly used to control particulate emission in bagasse -fired boilers. Reason [R]: Bagasse fly ash is abrasive primarily due to its high content of silica and Alumina.

A) [A] is true but [R] is false

B) Both [A] and [R] are true; and [R] is the correct explanation of [A]

C) [A] is false, [R] is true

D) Both [A] and [R] are true, but [R] is not the correct explanation of [A]

E) Answer not known

Explanation: Both the assertion and the reason are true statements, but the abrasiveness of the fly ash is not the reason why these control technologies are used; it is an independent characteristic of the ash.

121. The source of mercury in the Minamata bay was traced by a:

A) Chemical plant

B) Pulp and paper plant

C) Paint industry

D) Leather industry

E) Answer not known

Explanation: The source of mercury in Minamata Bay was a chemical plant discharging methylmercury into the bay, which led to Minamata disease.

122. Which of the following are incorrectly matched?

1. Odour and Taste - Chemical pollutants
2. Total Dissolved solids - Physical pollutants
3. Arsenic pollution - Herbicides and Pesticides
4. Chromium - Electroplating

A) (1) and (2)

B) (1) and (4)

C) (2) and (3)

D) (2) and (4)

E) Answer not known

Explanation: Total Dissolved Solids is a chemical parameter, not a physical one. Arsenic pollution is primarily from geological sources and industrial activities, not herbicides and pesticides.

123. Which of the followings are the raw materials used for the manufacture of the Pesticide BHC?

A) Benzene and Chlorine

B) Benzene and Hexane

C) Benzene and Ethanol

D) Benzene and Methanol

E) Answer not known

Explanation: Benzene Hexachloride (BHC) is produced by the chlorination of benzene and chlorine.

124. Cement is made by heating limestone with clay at ____ °C in a kiln.

A) 1600°C

B) 1450°C

C) 1200°C

D) 850°C

E) Answer not known

Explanation: The clinkering process in cement manufacturing involves heating limestone and clay to a temperature of about 1450°C.

125. In sugar production, the mixture of crystals and syrup is called as:

A) Massecuite

B) Solution

C) Molasses

D) Bagasse

E) Answer not known

Explanation: Massecuite is the mixture of sugar crystals and mother liquor (syrup) produced during the crystallization stage of sugar production.

126. Flue Gas Desulfurization (FGD) units in coal-based thermal power plants are primarily designed to:

A) Remove particulate matter

B) Reduce $SO_{2}$ emissions

C) Capture $CO_{2}$ emissions

D) neutralize acidic rain water

E) Answer not known

Explanation: Flue Gas Desulfurization (FGD) is a technology used to remove sulfur dioxide ($SO_{2}$) from the exhaust flue gases of power plants.

127. According to CPCB norms in India, which of the following best describes the treated effluent discharge limits for large pulp and paper mills?

A) BOD<100 mg/L, pH 4-10

B) BOD<30 mg/L, $TSS<50~mg/L$, pH 6.5-8.5

C) TDS<500 mg/L, $BOD<60~mg/L$

D) COD<500 mg/L, pH 5-9

E) Answer not known

Explanation: The Central Pollution Control Board (CPCB) has specific standards for treated effluent discharge from pulp and paper mills, with strict limits on BOD (<30 mg/L), TSS (<50 mg/L), and pH (6.5-8.5).

128. ____ types of plastic are recyclable.

A) 1, 2, 4, 5

B) 2, 3, 5, 6

C) 1, 3, 5, 7

D) 1, 2, 4, 6

E) Answer not known

Explanation: Plastics with recycling codes 1 (PET), 2 (HDPE), 4 (LDPE), and 5 (PP) are widely recyclable. Other types are often more difficult to recycle.

129. Inertial separators are primarily used for:

A) Collection of medium size and coarse particles

B) Collection of fine particles

C) Collection or respirable particles

D) Collection of toxic gases

E) Answer not known

Explanation: Inertial separators like cyclones use the inertia of particles to separate them from a gas stream, making them effective for medium and coarse particles.

130. Which of the following statements are true about the areas where cleaner production measures can be taken in:

1. Change of input materials
2. Technology change
3. Onsite reuse and recycling
4. Good operating practices

A) Only (i)

B) Only (iv)

C) Only (i) and (ii)

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

E) Answer not known

Explanation: Cleaner production is a holistic approach that involves all stages of production, including material inputs, technology, recycling, and operational practices.

131. In IWWM, the concept of water reclamation and reuse primarily aims to:

A) Increase fresh water withdrawals

B) Minimize wastewater generation

C) Conserve water resources by treating wastewater for safe reuse in agriculture industry or ground water recharge

D) Eliminate the need for treatment

E) Answer not known

Explanation: The main objective of water reclamation and reuse is to conserve water by finding alternative, safe uses for treated wastewater.

132. What do Volatile Suspended Solids (VSS) primarily represent in waste water analysis?

A) Inorganic mineral particles

B) Organic matter that can be turned off at high temperature

C) Dissolved solids

D) Heavy metals

E) Answer not known

Explanation: VSS represents the portion of suspended solids that is combustible and is used as an approximate measure of the organic content in wastewater.

133. Which of the following Indian Organization involved in the production of blue-green algae coated granulated compost from the solid waste?

A) Indian Agricultural Research Institute (IARI)

B) Indian Council for Medicinal Research (ICMR)

C) Botanical Survey of India (BSI)

D) Indian Institute of Science (IISC)

E) Answer not known

Explanation: IARI has developed technologies for producing value-added products from waste, including blue-green algae-coated compost.

134. What is the name of the device for continuously measuring waste water flow at or near ground surface?

A) Venturi meter

B) Turbine flow meter

C) Vortex flow meter

D) Parshall flame

E) Answer not known

Explanation: A Parshall flume is a specific type of open channel flow meter used to measure water flow in wastewater treatment plants.

135. While discharging the treated waste water into receiving water, it must be ensured that atleast ____ ppm of Dissolved Oxygen is present in it.

A) 4

B) 6

C) 10

D) 2

E) Answer not known

Explanation: A minimum dissolved oxygen (DO) level of 4 ppm is generally required for treated wastewater discharge to prevent harm to aquatic life in the receiving water body.

136. Which of the following statements are true about the method of treatment of an industrial waste depends on various factors such as:

1. Nature of industrial waste
2. BOD and COD of the effluent
3. Total solids present

A) (i) only

B) (ii) only

C) (i) and (ii) only

D) (i), (ii) and (iii)

E) Answer not known

Explanation: All three factors—the nature of the waste, its organic load (BOD and COD), and the amount of solids—are critical in selecting the appropriate treatment method.

137. Which wastes containing suspended matter in solid form, but little polluting matter in solution?

A) Coal washeries

B) Tanneries

C) Electroplating

D) Dairies

E) Answer not known

Explanation: Wastes from coal washeries are characterized by a high concentration of suspended solids (coal dust and clay) and a low concentration of dissolved pollutants.

138. Smoke particles are generally less that ____ μm.

A) 0.5

B) 1.0

C) 0.75

D) 0.25

E) Answer not known

Explanation: Smoke is a type of particulate matter resulting from incomplete combustion, and its particles are very fine, typically less than 0.5 μm.

139. A prominent method of natural disposal is:

A) Dilution

B) Mechanical straining

C) Sewage forming

D) Self purification

E) Answer not known

Explanation: Self-purification is the natural process by which a water body restores its quality through a combination of physical, chemical, and biological actions.

140. What does COD in waste water stand for?

A) Carbon Oxygen Demand

B) Combined Oxygen Demand

C) Chemical Oxygen Demand

D) Chemical Oxygen Degree

E) Answer not known

Explanation: COD is the acronym for Chemical Oxygen Demand, which is a measure of the amount of oxygen required for the chemical oxidation of pollutants in water.

141. The micro organism in wastewater is removed by:

A) Heating process

B) Hydrogenation process

C) Natural process

D) Oxidation process

E) Answer not known

Explanation: Microorganisms are removed from wastewater through various **oxidation processes**, such as biological treatment or chemical disinfection (e.g., chlorination).

142. Choose the correct usage of microelectrodes to determine:

1. Cyanide
2. Oxygen
3. Redox potential
4. Radio active elements

A) (1) and (4) are correct

B) (3) and (1) are correct

C) (2) and (3) are correct

D) (3) and (4) are correct

E) Answer not known

Explanation: Microelectrodes are specialized sensors used for in-situ measurements of parameters like dissolved oxygen and redox potential.

143. The over all reduction half reaction for decomposition of Biomass to methane is: $$CO_{2}+8H_{3}O^{+}+8e^{-} \rightarrow CH_{4}+10H_{2}O$$ Suggest under which condition this reaction occurs in water Bodies:

A) Anaerobic decomposition

B) Aerobic decomposition in the presence of sulphate

C) Aerobic decomposition in the presence of Nitrate

D) Aerobic decomposition with oxygen as primary oxidising agent

E) Answer not known

Explanation: This reaction represents the methanogenesis stage of anaerobic decomposition, where carbon dioxide is reduced to methane in the absence of oxygen.

144. How the ECOSAN concept is most beneficial in Agricultural field:

A) By the complete recovery of toxic metals from powered water sources

B) By the complete recovery of all nutrients from faces, urine and gray water

C) By the complete removal of toxic chemicals from waste water

D) By the complete recovery from microbial contaminants from waste water

E) Answer not known

Explanation: The ECOSAN concept (Ecological Sanitation) focuses on the safe recovery of nutrients from human waste and greywater for use as fertilizer in agriculture.

145. In acidic conditions, the protonated metal oxide surface, electro statically attract:

A) Cations

B) Anions

C) Amphoteric ions

D) Organic compounds

E) Answer not known

Explanation: In acidic conditions, the metal oxide surface becomes positively charged due to protonation and therefore attracts negatively charged ions, or anions.

146. Which of the following gas doesn't absorb infrared radiations?

A) $O_{2}$

B) $H_{2}O$

C) $CO_{2}$

D) $CH_{4}$

E) Answer not known

Explanation: Diatomic molecules with symmetrical bonds, such as $O_{2}$ and $N_{2}$, do not absorb infrared radiation. The other gases are greenhouse gases that do absorb infrared radiation.

147. Among the following water contaminants which one leads to skeletal fluorosis and hypocalcification?

A) Chloride

B) Fluoride

C) Phosphate

D) Calcium

E) Answer not known

Explanation: Excessive fluoride in drinking water can lead to skeletal fluorosis, a disease of the bones and joints, and hypocalcification of teeth.

148. In hydrocarbon analysis the flame ionization detector response is roughly proportional to the number of:

A) Catoms

B) Oatoms

C) H-atoms

D) N-atoms

E) Answer not known

Explanation: A flame ionization detector (FID) in a gas chromatograph measures hydrocarbons by responding to the number of carbon atoms that are ionized in a flame.

149. The indicator cannot be shared in solution because it:

A) Undergoes change in colour

B) Undergoes reduction reaction

C) Evaporates quickly

D) Decomposes overtime

E) Answer not known

Explanation: Many chemical indicators are unstable and can decompose over time, especially when exposed to light or air, making them unsuitable for long-term storage in solution.

150. Which of the following methods is involved in the green synthesis of (PET) polyethylene Terephthalate are:

1. Closed looped recycling
2. Open looped recycling
3. Methanolysis
4. Transesterification

A) (1), (3) and (4) are correct

B) (3), and (4) are correct

C) (2), and (3) are correct

D) (2), (3) and (4) are correct

E) Answer not known

Explanation: Methanolysis and transesterification are chemical recycling methods used in the green synthesis of PET by breaking the polymer down into its original monomers for reuse.

151. Match the gases in column A with their approximate percentage in the Earth's is atmosphere in column B

Column A (Gas)

1. Nitrogen ($N_{2}$)
2. Oxygen ($O_{2}$)
3. Argon (Ar)
4. Carbon Dioxide ($CO_{2}$)

Column B (Approximate % by volume)

1. 21%
2. 0.93%
3. 78%
4. 0.04%

A) (a)-3, (b)-1, (c)-2, (d)-4

B) (a)-1, (b)-2, (c)-3, (d)-4

C) (a)-4, (b)-3, (c)-1, (d)-2

D) (a)-2, (b)-4, (c)-1, (d)-3

E) Answer not known

Explanation: Nitrogen (78%), Oxygen (21%), Argon (0.93%), and Carbon Dioxide (0.04%) are the primary constituents of the Earth's atmosphere by volume.

152. If sulfur is returned to the atmosphere from the oceans the production of ____ is an important pathway.

A) $(CH_{3})_{2}S$

B) $NH_{4}HS$

C) $CaSO_{4}$

D) $Na_{2}SO_{3}$

E) Answer not known

Explanation: Dimethyl sulfide ($(CH_{3})_{2}S$) is a significant biogenic gas produced by marine phytoplankton and is a key pathway for sulfur to enter the atmosphere from the oceans.

153. Which of the following is the most important among biogenic hydrocarbons?

A) Methane

B) Ethane

C) Benzene

D) Toluene

E) Answer not known

Explanation: Methane is the most abundant biogenic hydrocarbon and a major greenhouse gas.

154. As the wind blows, soil particles are dislodged and begin to roll on the soil surface in a process called:

A) Soil mining

B) Soil flying

C) Soil washing

D) Saltation

E) Answer not known

Explanation: Saltation is a process of wind erosion where soil particles are lifted and transported in a bouncing or rolling motion along the ground surface.

155. The biodegradation process of surface soil is inhibited due to the presence of:

A) Carbon- rich Nitrogen poor nutrients

B) Nitrogen rich and phosphorus poor nutrients

C) Chloride - rich and sodium poor nutrients

D) Nitrogen rich and carbon poor nutrients

E) Answer not known

Explanation: Biodegradation in soil requires a balanced C:N ratio. A high carbon-to-nitrogen ratio (carbon-rich, nitrogen-poor) limits microbial growth and inhibits the decomposition process.

156. Which of the following waste is also known as "end of life" (EOL)?

A) Biomedical waste

B) Radioactive waste

C) e- waste

D) Plastic waste

E) Answer not known

Explanation: E-waste (electronic waste) is often referred to as "end-of-life" waste because it consists of discarded electronic devices that have reached the end of their useful lifespan.

157. Who is the pioneering legislation for e-waste management?

A) The SWISS EE - 1996

B) The SWISS OREE - 1995

C) The SWISS ORDEE - 1998

D) The SWISS ORRDE - 1990

E) Answer not known

Explanation: The Swiss Ordinance on the Return, Take-back, and Disposal of Electrical and Electronic Equipment (OREE), which came into force in 1998, is considered pioneering, but the precursor to this, also known by a similar name, was developed in 1995.

158. Arrange the layers of secure landfills in chronological order

1. A thick polythene liner
2. Absorbent cushion layer
3. Clay layer
4. Gravel layer

A) (i), (ii), (iii), (iv)

B) (iv), (ii), (i), (iii)

C) (iii), (iv), (i), (ii)

D) (ii), (iii), (iv), (i)

E) Answer not known

Explanation: The correct order of a secure landfill liner system is typically: a compacted clay layer (iii), followed by a gravel drainage layer (iv), a synthetic (polythene) liner (i), and an absorbent cushion layer (ii) to protect the liner.

159. Deleberately dismantiling buildings the salvage materials for reuse is known as:

A) Recycling

B) Waste segregation

C) Deconstruction

D) Source reduction

E) Answer not known

Explanation: Deconstruction is the systematic dismantling of a building to maximize the recovery of materials for reuse and recycling, as opposed to demolition where materials are often destroyed.

160. The hazardous and other wastes (management and Transboundary movement) rules were published by the Government of India in the ministry of Environment, forest and climate change in:

A) January 25, 2000

B) March 20, 2003

C) May 15, 2009

D) July 24, 2015

E) Answer not known

Explanation: The Hazardous and Other Wastes (Management and Transboundary Movement) Rules were published on April 4, 2016, not on any of the dates listed.

161. The only state which is successfully running waste-to-electricity plants through anaerobic digestion in India is:

A) Gujarat

B) Sikkim

C) Tamil Nadu

D) Assam

E) Answer not known

Explanation: Assam has been successfully running waste-to-electricity plants using anaerobic digestion.

162. Metal present in printed circuit board and cables acts as catalyst for dioxin formation.

A) Mercury

B) Fluoride

C) Copper

D) Magnesium

E) Answer not known

Explanation: During the incineration of e-waste, copper acts as a catalyst for the formation of toxic dioxins.

163. Among the following polymers, which one is thermoplastics in nature:

A) Aliphatic polyester

B) Epoxy polymers

C) Carboxymethyl cellulose

D) Polystyrene

E) Answer not known

Explanation: Polystyrene is a thermoplastic, meaning it can be repeatedly softened by heating and hardened by cooling.

164. Which one of the following polymer does not undergo hydrolysis and hydrobio degradability?

A) Polyesters

B) Polyamides

C) Polyurethanes

D) Polypropylene

E) Answer not known

Explanation: Polypropylene is a synthetic polymer that is highly resistant to degradation by water (hydrolysis) and microorganisms (hydrobiodegradability).

165. Select the correct prime objective of solid waste management from the given statements:

1. Solid waste mount to environmental threat.
2. To trim down the disposal of solid waste along with salvaging material.
3. Energy from solid wastes.
4. To reduce pollution load in ground level.

A) (i), (ii), (iii), (iv)

B) (i), (ii), (iii)

C) (ii), (iii)

D) (i), (ii), (iv)

E) Answer not known

Explanation: The primary objectives are to minimize waste for disposal (ii) and recover energy from it (iii). Statements (i) and (iv) describe problems and outcomes, not objectives.

166. During the recycling of paper waste ____ used as bleaching agent.

A) HCl or $H_{2}SO_{4}$

B) $CO_{2}$

C) NaOH

D) $H_{2}O_{2}$ or chlorine oxide

E) Answer not known

Explanation: Hydrogen peroxide ($H_{2}O_{2}$) and chlorine oxide are common bleaching agents used to whiten paper pulp during the recycling process.

167. In rehabilitation excavating and re-disposing waste is more controlled and environmentally sound manner called:

A) Leachate management

B) Slope stabilization

C) Phased approach

D) Landfill mining

E) Answer not known

Explanation: Landfill mining is the process of excavating a landfill to recover materials or reclaim land, often as part of a rehabilitation effort.

168. Which of the following are resilient and almost impossible to compact?

A) Plastics

B) Tires

C) Chemicals

D) E-waste

E) Answer not known

Explanation: Tires are highly resilient and difficult to compact due to their material properties, posing a challenge for landfilling.

169. Applying specifically engineered and micro organisms that are designed to break down contaminant is called:

A) In situ bioremediation

B) Ex situ bioremediation

C) Biostimulation

D) Bioaugmentation

E) Answer not known

Explanation: Bioaugmentation is the practice of adding cultured microorganisms to a site to accelerate the biodegradation of specific contaminants.

170. The process by which a water body becomes overly enriched with nutrients leading to excessive growth of algae and other plant life called:

A) Oligotrophication

B) Eutrophication

C) Subtrophication

D) Zerotrophication

E) Answer not known

Explanation: Eutrophication is the process of a water body becoming overly enriched with nutrients, often leading to algal blooms.

171. Difference in the level of oxygen is the expression of the capacity to consume oxygen by the sewage, which is expressed in:

A) PPM-Parts Per Million

B) RPM- Revolution Per Minute

C) MPL-Moles Per Liter

D) GPL-Grams Per Liter

E) Answer not known

Explanation: The oxygen consumption capacity of sewage (BOD or COD) is a measure of concentration, and is typically expressed in mg/L, which is equivalent to parts per million (PPM).

172. When the wastes generated at traffic congested locations will be collected?

A) During early morning

B) During night hours

C) First part of the day

D) Second part of the day

E) Answer not known

Explanation: Waste collection in traffic-congested areas is often done at night hours to avoid disrupting daytime traffic flow.

173. Which of the statements given below are correct?

1. Density separation of solid wastes can be accomplished by air classifiers.
2. Iron recovery from solid wastes can be done by magnetic separators.
3. Aluminium separation can be done by eddy current separators.

A) (i) and (ii) only

B) (ii) and (iii) only

C) (i) and (iii) only

D) (i), (ii) and (iii)

E) Answer not known

Explanation: All three statements are correct. Air classifiers use density, magnetic separators use magnetism, and eddy current separators use induced currents to separate different types of solid waste materials.

174. Match the following proximate analysis with their formulas.

a. Moisture
b. Volatile matter
c. Ash
d. Fixed carbon

1. $\% = (\frac{Weight~of~residue}{Weight~of~sample})\times100$
2. $(\%)=(\frac{Weight~loss}{Weight~of~the~sample}\times100)$
3. $(\%)=100-(\%M+\%Ash+\%VM)$
4. (Total weight loss - moisture)

A) (a)-2, (b)-4, (c)-1, (d)-3

B) (a)-1, (b)-3, (c)-2, (d)-4

C) (a)-3, (b)-1, (c)-4, (d)-2

D) (a)-4, (b)-2, (c)-3, (d)-1

E) Answer not known

Explanation: Moisture is calculated from weight loss (2), volatile matter from the difference in weight loss (4), ash from the residue (1), and fixed carbon by difference (3).

175. Match the following

a. Garbage
b. Rubbish
c. Ashes
d. Bulky house hold waste

1. Lawn mowers
2. Attracts flies and insects
3. Incinerated to flames at $1400-1500^{\circ}F$
4. Cinders and clinkers

A) (a)-2, (b)-3, (c)-4, (d)-1

B) (a)-3, (b)-4, (c)-1, (d)-2

C) (a)-4, (b)-1, (c)-2, (d)-3

D) (a)-1, (b)-2, (c)-3, (d)-4

E) Answer not known

Explanation: Garbage is decomposable waste that attracts pests (2). Rubbish is non-putrescible waste that is often incinerated (3). Ashes are the residue of combustion (4). Bulky household waste includes large items like lawn mowers (1).

176. Identify the kind of waste subjected to decay with time and evolve highly offensive odour and gases which are detrimental to health:

A) Organic waste

B) Inorganic waste

C) Trade waste

D) Ashes

E) Answer not known

Explanation: Organic waste, such as food scraps and garden waste, decomposes over time, producing foul-smelling gases that can be harmful.

177. Solid wastes can be made to use for:

A) Packing

B) Transportation

C) Recycling

D) Municipal earnings

E) Answer not known

Explanation: Recycling is the process of converting solid waste materials into new materials and objects, making them useful again.

178. Rubbish consists of all non-putrescible wastes excluding:

A) Rags

B) Paper

C) Ashes

D) Broken crokery

E) Answer not known

Explanation: Rubbish generally refers to non-putrescible solid wastes but typically excludes ashes, which are a separate category of non-combustible residue.

179. Arrange the following stages of composting in chronological order.

1. Stabilisation stage
2. Seiving and product grading
3. Maturation stage
4. High rate composting stage

A) (i), (iii), (iv), (ii)

B) (iii), (i), (iv), (ii)

C) (iv), (i), (iii), (ii)

D) (i), (iv), (iii), (ii)

E) Answer not known

Explanation: The correct sequence for composting is: High rate composting (iv), followed by Stabilization (i), Maturation (iii), and finally Sieving and product grading (ii).

180. Incineration is a chemical reaction that can reduce solid waste to about:

A) 90% in volume and 75% in weight

B) 75% in volume and 90% in weight

C) 55% in volume and 80% in weight

D) 80% in volume and 55% in weight

E) Answer not known

Explanation: Incineration can reduce the volume of solid waste by a significant amount, typically around 90%, and the weight by approximately 75%.

181. Which one of the following is most destructive in killing the pathogens?

A) Hypochlorite ion

B) Hypochlorous acid

C) Mono-Chloramine

D) Di-Chloramine

E) Answer not known

Explanation: Hypochlorous acid (HOCl) is the most effective disinfectant produced when chlorine is added to water, as it can readily penetrate the cell walls of pathogens.

182. Which of the following best represents Carbon's ability to remove taste and Odour compounds?

A) Solubility

B) Adsorption capacity

C) Chemical reactivity

D) Ion exchange capacity

E) Answer not known

Explanation: Activated carbon is used for taste and odour removal due to its high adsorption capacity, where compounds are attracted and held to the large surface area of the carbon.

183. The content of secondary sedimentation tank of an activated sludge process would predominantly ____ under go to give off clarified effluent.

A) Type III zone settling

B) Type II flocculent settling

C) Type IV compression settling

D) Floatation settling

E) Answer not known

Explanation: In a secondary sedimentation tank, the high concentration of activated sludge leads to hindered or zone settling, which is classified as Type III settling.

184. In wastewater treatment, particles that change size, shape and specific gravity when in contact with each other can be removed by:

A) Precipitation

B) Flocculation

C) Settling in contiguous zone

D) Compression or compaction

E) Answer not known

Explanation: Flocculation is the process of chemical and physical interactions that cause small particles to clump together into larger, more easily settleable masses called flocs.

185. Compute the hydraulic loading rate of an ion-exchange column, if the flow rate of 5000 $m^{3}/h$ with the total cross-sectional area of 25 $m^{2}$.

A) 12500 m/h

B) 12.5 m/h

C) 200 m/h

D) 20000 m/h

E) Answer not known

Explanation: Hydraulic loading rate is calculated by dividing the flow rate by the cross-sectional area: 5000 $m^{3}/h$ / 25 $m^{2}$ = 200 m/h.

186. The adsorption destabilization with ____ is one of the themes of coagulation theory.

A) Negatively charged, polynuclear Aluminium Species

B) Positively charged, mononuclear Aluminium species

C) Positively charged, polynuclear Aluminium species

D) Negatively charged, mononuclear Aluminum species

E) Answer not known

Explanation: Coagulation works by using positively charged, polynuclear aluminium species to adsorb onto negatively charged particles, neutralizing their charge and causing them to clump together.

187. In disinfection process, bromine is added as bromine chloride gas which reacts with water to give:

A) HOBr

B) $Br_{2}Cl_{2}$

C) HBr

D) $H_{2}O_{2}$

E) Answer not known

Explanation: Bromine chloride gas hydrolyzes in water to form hypobromous acid (HOBr), which is a powerful disinfectant.

188. In Reverse Osmosis, the pressure on the solution side that is higher than the osmotic pressure will result in increase in:

A) Flux momentum

B) Flux density

C) Flux volume

D) Flux mass

E) Answer not known

Explanation: The driving force in reverse osmosis is the applied pressure. Increasing this pressure above the osmotic pressure increases the mass flux of water through the membrane.

189. It is always desirable to have a large Height-To-Diameter (H:D) for a fixed-bed adsorption column, and it ranges from:

A) 1:3 to 1:5

B) 2:4 to 3:9

C) 6:1 to 9:3

D) 3:1 to 5:1

E) Answer not known

Explanation: A large H:D ratio, typically between 3:1 and 5:1, is preferred for fixed-bed adsorption columns to ensure efficient contact time and uniform flow.

190. The saturated dissolved oxygen concentration in tap water at $20^{\circ}C$ is about:

A) 12.48 Mg/L

B) 6.80 Mg/L

C) 9.17 Mg/L

D) 14.23 Mg/L

E) Answer not known

Explanation: The saturated dissolved oxygen concentration in fresh water at 1 atm and 20°C is approximately 9.17 mg/L.

191. In a rectangular clarification basin, the flow is 30,300 $m^{3}/day$. The over flow rate is 24.4 $m^{3}/d-m^{2}$ and the detention time is 6h. Compute the required plan area.

A) 1242 $m^{2}$

B) 2484 $m^{2}$

C) 3726 $m^{2}$

D) 4968 $m^{2}$

E) Answer not known

Explanation: Plan area is calculated by dividing the flow rate by the overflow rate: 30,300 $m^{3}/day$ / 24.4 $m^{3}/d-m^{2}$ = 1241.8 $m^{2}$, which is closest to 1242 $m^{2}$.

192. If the effluent quality has stringent discharge limits and contains concentrated acids or bases, ____ neutralisation system should be used.

A) Continuous

B) Batch

C) Fed-Batch

D) Semi-continuous

E) Answer not known

Explanation: A batch neutralization system provides more control and is safer for treating effluent with highly concentrated acids or bases to meet stringent discharge limits.

193. If the influent flow of wastewater is relatively constant and effluent chemistry is not very critical ____ neutralization practice will be employed.

A) Batch

B) Semi-continuous flow

C) Continuous flow

D) Fed batch

E) Answer not known

Explanation: A continuous flow neutralization system is more suitable and cost-effective for treating wastewater with a relatively constant flow and less critical effluent quality.

194. The solid-liquid interface for type III and IV suspensions can be observed through the plot of:

A) Time versus velocity

B) Time versus distance settled

C) Time versus viscosity

D) Time versus density

E) Answer not known

Explanation: The settling characteristics of Type III (zone) and Type IV (compression) suspensions are determined by monitoring the height of the solid-liquid interface over time versus distance settled.

195. How the grits will get removed if the primary treatment unit does not have any grit chamber?

A) Removed in aeration basin and secondary classifier

B) Removed in tricking filter and secondary classifier

C) Removed in bio filters

D) Removed in Rotating Biological contactors

E) Answer not known

Explanation: Without a dedicated grit chamber, heavy, inorganic grit particles will settle in other parts of the system, such as the aeration basin and secondary clarifier, causing operational problems.

196. The velocity of the Bar screen and opening size of the bar is:

A) <1 m/sec and < 40 mm

B) <0.1 m/sec and < 4 mm

C) 1.2 to 1.5 m/sec and 45 to 60 mm

D) >2 m/ sec and 50 mm

E) Answer not known

Explanation: To prevent excessive head loss and the pushing of organic matter through the screen, the velocity is kept low, typically less than 1 m/s, and the opening size is less than 40 mm.

197. In waste water treatment plant, mechanical bar screens are typically installed at an angle of ____ with the horizontal

A) 45° to 90°

B) 0° to 30°

C) 100° to 180°

D) 200° to 270°

E) Answer not known

Explanation: Mechanical bar screens are installed at an angle between 45° and 90° to facilitate the easy removal of screenings by the mechanical rake.

198. If the concentration and flow of nitrogen in the influent to a wastewater plant are 45 Mg/L and 50 L/s respectively, then the total nitrogen load is:

A) 194 kg N/d

B) 0.194 kg N/d

C) 96 kg N/d

D) 0.096 kg N/d

E) Answer not known

Explanation: The total nitrogen load is calculated by multiplying the flow rate by the concentration: (50 L/s) * (45 mg/L) * (86,400 s/d) / (1,000,000 mg/kg) = 194.4 kg N/d, which is closest to 194 kg N/d.

199. In a grit chamber, if a flume is not free-flowing and has backwater effects ____ is a function of the difference in upstream and downstream heads

A) Discharge

B) Velocity

C) Pressure head

D) Drift velocity

E) Answer not known

Explanation: When a flume is not free-flowing, the discharge rate is influenced by the difference in water levels upstream and downstream, not just the upstream head.

200. For a horizontal flow grit chamber, the ideal settling theory assumes that the horizontal velocity is:

A) uniform over depth

B) varying over depth

C) uniform over length

D) varying over length

E) Answer not known

Explanation: The ideal settling theory for a horizontal flow grit chamber simplifies the fluid dynamics by assuming that the horizontal velocity is uniform over depth.

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