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Past Questions — 2026
Which testing method is widely recognized as the traditional “3-point method” for measuring the resistance of an existing earth electrode?
A)
Wenner Four-Pin Method
B)
Schlumberger Method
C)
Fall-of-Potential Method
D)
Clamp-on Loop Testing Method
Option C is correct: Fall-of-Potential Method.
According to Kirchhoffs voltage law, the algebraic sum of all IR drops and e.m.fs. in any closed loop of a network is always:
A)
negative
B)
positive
C)
determined by battery e.m.fs.
D)
zero
Option D is correct: zero.
What happens to the secondary circuit of a Potential Transformer (PT) under normal operating conditions?
A)
It is practically short-circuited
B)
It is practically open-circuited (high impedance connected to relays/meters)
C)
It carries full-load line current
D)
It is maintained at ground potential
Option B is correct: It is practically open-circuited (high impedance connected to relays/meters).
Why is electrical power transmitted at very high voltages?
A)
To minimize line losses ( I²R losses) and reduce the cost of conductors
B)
To increase the frequency of the supply
C)
To make it easier to step down for domestic use
D)
To protect transformers from lightning
Option A is correct: To minimize line losses ( I²R losses) and reduce the cost of conductors.
Effect of moisture on the insulating material is to:
A)
increase dielectric constant
B)
increase dielectric strength
C)
decrease insulation resistance
D)
decrease dielectric loss
Option C is correct: decrease insulation resistance.
Which protection device is installed to prevent the ingress of moisture and air into the transformer’s main oil tank?
A)
Buchholz relay
B)
Breather
C)
Conservator tank
D)
Explosion vent
Option B is correct: Breather.
Land disposal of sewage will be favourable where:
A)
The rivers run dry or have a small flow during summer
B)
Rainfall is very high
C)
Climate is wet and rates of evaporation is low
D)
The sewage arriving at the out fall point is fresh and non-septic
Land disposal of sewage (such as sewage farming or land application) involves applying sewage to the soil for treatment and disposal. For this method to be favorable and effective, the following conditions must be met:
1. **Fresh Sewage (Option d):** Sewage must be 'fresh' and 'non-septic'. If sewage becomes septic (anaerobic) during transport, it develops foul odors (H2S gas) and becomes difficult to handle, making it unsuitable for land application near populated areas. Fresh sewage contains dissolved oxygen and organic matter that can be more effectively utilized by soil microbes and plants.
2. **Why Option a is incorrect:** If rivers run dry, it might make land disposal a *necessity* due to lack of water bodies for dilution, but it doesn't make the process of land disposal itself 'favorable' or technically efficient.
3. **Why Option b is incorrect:** Very high rainfall is detrimental to land disposal. Excessive rain leads to waterlogging, prevents the soil from absorbing the sewage, and increases the risk of sewage runoff contaminating nearby surface water bodies.
4. **Why Option c is incorrect:** A wet climate with low evaporation rates leads to saturation of the soil. For land disposal to work, the soil must have the capacity to absorb the liquid (percolation) and the environment should ideally support evaporation to prevent the water table from rising too high.
A septic tank is a:
A)
Sedimentation tank
B)
Digestion tank
C)
Combination of sedimentation and digestion tank
D)
Aeration tank
A septic tank is a primary wastewater treatment unit designed to treat domestic sewage. It functions through two simultaneous processes:
1. Sedimentation: As sewage enters the tank, the flow velocity decreases, allowing heavy organic solids to settle at the bottom to form a layer of sludge. Simultaneously, lighter materials like grease and oil float to the top to form a scum layer.
2. Digestion: The settled sludge undergoes anaerobic digestion, where anaerobic bacteria break down the complex organic matter into simpler compounds, gases (like methane and carbon dioxide), and water.
Therefore, it acts as both a sedimentation tank and a digestion tank.
Why other options are incorrect:
- Option (a) is incomplete because it ignores the biological digestion process.
- Option (b) is incomplete because digestion cannot occur efficiently without the prior sedimentation of solids.
- Option (d) is incorrect because a septic tank is strictly an anaerobic process; aeration tanks are used in aerobic treatment processes (like Activated Sludge Process), which is the opposite of how a septic tank operates.
A pipe used to carry discharge from sanitary fittings like bathrooms, kitchens etc. is called:
A)
Soil pipe
B)
Waste pipe
C)
Vent pipe
D)
Upvc pipe
In plumbing and environmental engineering, pipes are categorized based on the type of effluent they carry:
1. **Waste Pipe (Option b):** This pipe is specifically designed to carry liquid waste (sullage) from sanitary fittings such as washbasins, kitchen sinks, and bathrooms. This waste does not contain human excreta.
2. **Soil Pipe (Option a):** This pipe carries 'soil' or human excreta from water closets (WCs) and urinals to the sewer or septic tank.
3. **Vent Pipe (Option c):** This is a pipe provided to allow the escape of foul gases from the drainage system to the atmosphere and to maintain atmospheric pressure within the pipes to prevent siphonage of traps.
4. **uPVC Pipe (Option d):** This refers to the material (Unplasticized Polyvinyl Chloride) used to make the pipes, not the functional classification of the pipe based on the discharge it carries.
Since the question specifies discharge from bathrooms and kitchens (sullage), the correct term is Waste pipe.
Which of the following statement is correct?
A)
Sewage if not treated, will create healthy conditions
B)
Secondary treatment of sewage works on hydraulic separation principles
C)
Primary clarifiers are the sedimentation tanks located just after the grit chambers
D)
Trickling filter is different from percolating filter
Step-by-step analysis of the options:
1. Option (a) is incorrect: Untreated sewage contains pathogens, organic matter, and toxic chemicals. If not treated, it leads to water pollution, outbreaks of diseases (like cholera and typhoid), and eutrophication, creating unhealthy conditions, not healthy ones.
2. Option (b) is incorrect: Secondary treatment is a biological process (e.g., Activated Sludge Process, Trickling Filters) that uses microorganisms to decompose organic matter. Hydraulic separation (physical removal of solids based on density/gravity) is the principle used in Primary treatment.
3. Option (c) is correct: In a typical wastewater treatment plant flow, the sequence is: Screening $\rightarrow$ Grit Chamber $\rightarrow$ Primary Clarifier (Primary Sedimentation Tank). The grit chamber removes heavy inorganic solids (sand, gravel), and the primary clarifier follows to remove settleable organic solids.
4. Option (d) is incorrect: In the context of environmental engineering, a trickling filter is essentially a type of percolating filter. Both refer to attached-growth biological processes where sewage is sprayed over a bed of media (rocks, plastic) to allow a biofilm to degrade organic matter.
The breaking up of cohesion in a mass of concrete is called:
A)
Workability
B)
Bleeding
C)
Segregation
D)
Creep
Step-by-step reasoning:
1. Definition of Segregation: Segregation in concrete occurs when the coarse aggregates separate from the cement paste (mortar). This represents a loss of homogeneity and a 'breaking up of cohesion' within the concrete mass, often caused by over-vibration, dropping concrete from a height, or improper mix design.
2. Analysis of other options:
- Workability (a): This refers to the ease with which concrete can be mixed, placed, consolidated, and finished. It is a property of fresh concrete, not a failure of cohesion.
- Bleeding (b): This is a specific form of segregation where water (a liquid) rises to the surface of freshly placed concrete. While related to segregation, bleeding refers specifically to the movement of water, whereas the general breaking up of cohesion of the mass is termed segregation.
- Creep (d): This is the time-dependent permanent deformation of concrete under a sustained constant load. It is a long-term structural property, not a phenomenon occurring during the fresh state of concrete.
3. Conclusion: The process of the concrete mass losing its cohesive unity and separating into its constituent parts is defined as segregation.
In india per capita contribution of dry solids to be assumed at:
A)
40 g/day
B)
50 g/day
C)
60 g/day
D)
70 g/day
In Environmental Engineering, specifically regarding the design of sewage treatment plants and the estimation of sludge production, the per capita contribution of dry solids (suspended solids) to domestic sewage is a critical parameter. According to standard Indian standards and textbooks on Environmental Engineering (such as those by S.K. Garg or B.C. Punmia), the average per capita contribution of dry solids in India is generally assumed to be approximately 70 grams per day. This value is used to calculate the total organic load and the volume of sludge that needs to be handled in waste water treatment processes. Options a, b, and c (40g, 50g, and 60g) are lower than the standard design assumption used for Indian urban populations.
The water of a river has an important property called:
A)
Turbidity
B)
Self purification
C)
Permeability
D)
Infiltration capacity
Step-by-step reasoning: 1. Analysis of the question: The question asks for an 'important property' specific to river water in the context of Environmental Engineering. 2. Evaluating Option (b) Self purification: This is a fundamental ecological and engineering property of flowing water bodies (lotic systems). Self-purification is the natural process by which a river cleanses itself of organic pollutants through mechanisms such as dilution, sedimentation, oxidation (aeration), and biological degradation by microorganisms. This is a critical concept in wastewater engineering (e.g., calculating BOD and dissolved oxygen sag curves). 3. Evaluating Option (a) Turbidity: While river water has turbidity, this is a characteristic or a measurement of water quality (cloudiness), not a functional 'property' that defines the river's behavior or capacity to recover from pollution. 4. Evaluating Option (c) Permeability: Permeability is a property of soil or porous media (the riverbed), not a property of the water itself. 5. Evaluating Option (d) Infiltration capacity: Similar to permeability, infiltration capacity refers to the maximum rate at which soil can absorb water; it is a property of the land/soil, not the river water. Therefore, self-purification is the only option that describes a functional property of the river water system.
For a structure subjected to the action of sea water, the cement used is:
A)
Rapid hardening cement
B)
Low heat cement
C)
High alumina cement
D)
Sulphate resisting cement
Step-by-step reasoning: 1. Sea water contains high concentrations of soluble salts, specifically sulphates (such as magnesium sulphate and sodium sulphate) and chlorides. 2. When ordinary Portland cement (OPC) is used in sea water, the sulphates react with the tricalcium aluminate (C3A) in the cement to form ettringite. This reaction causes expansion, cracking, and eventual disintegration of the concrete (known as sulphate attack). 3. Sulphate Resisting Cement (SRC) is specifically formulated with a very low C3A content (typically less than 5%), which prevents the formation of expansive ettringite, making it the ideal choice for marine structures. 4. Analysis of other options: (a) Rapid hardening cement is used for quick strength gain (e.g., road repairs) and does not provide chemical resistance. (b) Low heat cement is used for mass concreting (e.g., dams) to prevent thermal cracking, not specifically for chemical attack. (c) High alumina cement is used for refractory purposes or very rapid strength, but it can be unstable in certain temperature conditions and is not the standard choice for general sea water resistance compared to SRC.
The hammer blow in pipes occurs when:
A)
There is excessive leakage in the pipe
B)
The pipe bursts under high pressure of fluid
C)
The flow of fluid through the pipe is suddenly brought to rest by closing the valve
D)
The flow of fluid through the pipe is gradually brought to rest by closing the valve
The phenomenon described is known as 'Water Hammer'. It occurs when a fluid in motion is forced to stop or change direction suddenly. When a valve is closed rapidly, the kinetic energy of the moving fluid is converted into a high-pressure surge (pressure wave) that travels back through the pipe. This sudden increase in pressure creates a shock wave that can cause loud banging noises (the 'hammer' sound) and can potentially rupture pipes or damage fittings.
Analysis of options:
- Option (a) is incorrect because leakage generally reduces pressure rather than creating a shock wave.
- Option (b) is a potential consequence of water hammer, but it is not the cause of the hammer blow itself.
- Option (c) is correct as the 'sudden' stop is the critical trigger for the pressure surge.
- Option (d) is incorrect because a gradual closure allows the fluid to decelerate slowly, preventing the buildup of a high-pressure shock wave.
The minimum grade of concrete for small capacity of tanks upto 50 cum at a locations where there is difficulty in providing M-30 grade of concrete, may be taken as:
A)
M-10 grade of concrete
B)
M-15 grade of concrete
C)
M-20 grade of concrete
D)
M-25 grade of concrete
According to the Indian Standard code for the design of liquid retaining structures (IS 3370), the general requirement for the grade of concrete used in water tanks is M-30 to ensure durability and water-tightness. However, the code provides a relaxation for small-capacity tanks. For tanks with a capacity up to 50 cubic meters, in locations where it is difficult to provide M-30 grade concrete, the minimum grade of concrete permitted is M-20. This allows for practical construction in remote areas while still maintaining a minimum threshold of structural integrity and permeability resistance. Options a (M-10) and b (M-15) are too low for liquid retaining structures as they lack the necessary density and strength to prevent seepage and corrosion of reinforcement. Option d (M-25) is higher than the minimum required relaxation limit of M-20.
A combined system of sewer will be favourable when:
A)
The sewers are to be laid in rocks
B)
The finance are limited
C)
The topography is flat necessitating deep excavation for combined system
D)
The locality to be served has narrow streets
A combined sewer system carries both domestic sewage and storm water in a single pipe, whereas a separate system requires two distinct sets of pipes.
1. Why Option (d) is correct: In areas with narrow streets, there is insufficient physical space to lay two separate parallel pipelines (one for sewage and one for storm water) without causing extreme congestion or interfering with other utilities. A single combined pipe is the most practical solution in such constrained urban environments.
2. Why Option (a) is incorrect: Laying sewers in rock is expensive and difficult. A combined system requires much larger diameter pipes to handle peak storm flows compared to a separate sanitary sewer. Excavating larger trenches in rock is significantly more costly than excavating smaller ones.
3. Why Option (b) is incorrect: While it might seem that one pipe is cheaper than two, combined systems often require much larger pipes and massive treatment plants capable of handling huge volumes of diluted sewage during rains, which can increase long-term capital and operational costs.
4. Why Option (c) is incorrect: In flat topography, deep excavation is already a challenge. Because combined sewers must be larger to accommodate storm water, they often require deeper excavations to maintain the necessary gradient (slope) for gravity flow, making them less favorable in flat terrains compared to separate systems.
Grit chambers of sewage plant are usually changed after:
A)
1 day
B)
1 week
C)
2 weeks
D)
4 weeks
In a sewage treatment plant, grit chambers are designed to remove inorganic solids (such as sand, gravel, and eggshells) through sedimentation. These materials are non-biodegradable and highly abrasive. If allowed to accumulate for long periods, they can cause significant wear and tear on downstream pumps, clog pipes, and reduce the effective volume of subsequent treatment units (like primary clarifiers). Therefore, to maintain operational efficiency and prevent equipment damage, grit chambers are typically cleaned or 'changed' (emptied of accumulated grit) on a daily basis. Options b, c, and d (1 week to 4 weeks) are incorrect because allowing grit to accumulate for such durations would lead to operational failure and excessive mechanical wear.
The specific gravity of stone should not, in any case, be less than:
A)
1%
B)
1.5%
C)
2%
D)
2.5%
Specific gravity is the ratio of the weight of a given volume of a material to the weight of an equal volume of water. For building stones, specific gravity is a key indicator of density and strength. Generally, most building stones have a specific gravity ranging between 2.4 and 2.8. According to standard engineering specifications for construction materials, the specific gravity of a stone used for structural purposes should not be less than 2.5. If the specific gravity is lower than this, the stone is typically too porous or lacks the necessary density to provide the required compressive strength and durability for engineering works. Note: While specific gravity is a dimensionless ratio, the options in this specific exam question are presented with percentage signs (%), which is a common typographical error in some departmental exam papers; however, the numerical value 2.5 remains the standard technical threshold.
Sewage treatment plant is normally designed to meet the requirement of ___________ period after completion.
A)
15 years
B)
20 years
C)
30 years
D)
50 years
In Environmental Engineering and Urban Planning, the 'design period' is the number of years for which a facility is designed to be adequate to meet the needs of the population. For Sewage Treatment Plants (STPs), the standard design period is typically taken as 30 years. This timeframe is chosen to balance the high capital cost of construction with the expected growth in population and sewage generation. Designing for a shorter period (e.g., 15 or 20 years) would lead to premature obsolescence and frequent expensive expansions, while designing for too long a period (e.g., 50 years) would lead to excessive initial costs and potential inefficiency due to over-sizing of biological processes (which can lead to poor treatment quality if the actual load is too low).
Which of the following methods aim for a comprehensive and rational solution to the design of RCC structure by considering safety at ultimate loads and serviceability at working loads?
A)
Limit state method
B)
Working stress method
C)
Direct design method
D)
Ultimate load method
The Limit State Method (LSM) is a modern approach to structural design that ensures a structure is safe and functional throughout its intended life. It addresses two primary criteria: 1. Limit State of Collapse (Ultimate Loads): This ensures the structure does not fail under maximum expected loads (safety). 2. Limit State of Serviceability (Working Loads): This ensures the structure remains functional under normal everyday loads by controlling deflection and cracking.
Comparison with other options:
- Working Stress Method (WSM): This is a traditional method based on linear elastic theory. It focuses only on keeping stresses within a permissible limit (working loads) and does not explicitly account for the ultimate strength or safety factors for loads.
- Direct Design Method: This is a specific procedure used for the analysis of two-way slabs, not a general philosophy for RCC design safety and serviceability.
- Ultimate Load Method: This focuses solely on the collapse load (strength) and ignores serviceability requirements like deflection and crack width.
The failure of foundation of a building is due to:
A)
Over loaded
B)
Unequal settlement of soil
C)
Present of sub soil moisture
D)
Increasing the depth of footing
In foundation engineering, the stability of a structure depends not only on the bearing capacity of the soil but also on the uniformity of the settlement.
1. **Unequal (Differential) Settlement (Option b):** This is the most critical cause of foundation failure. When different parts of a building settle by different amounts, it induces secondary stresses (shear and bending) in the superstructure (beams, columns, and walls) for which they were not designed. This leads to structural cracking, tilting, and eventually total failure of the building.
2. **Overloading (Option a):** While overloading can lead to shear failure of the soil, most foundations are designed with a Factor of Safety (FoS). A building is more likely to suffer from differential settlement long before it reaches the ultimate bearing capacity of the soil.
3. **Sub-soil moisture (Option c):** Moisture can contribute to settlement (e.g., in expansive clays), but the 'failure' itself is the resulting movement (settlement) rather than the mere presence of moisture.
4. **Increasing depth of footing (Option d):** Increasing the depth of the footing generally improves stability by reaching denser soil strata and increasing the bearing capacity; it is a remedial measure, not a cause of failure.
A long column is one whose ratio of effective length to its least lateral dimension exceeds:
A)
5
B)
10
C)
12
D)
20
In Reinforced Concrete Design (RCC), columns are classified as either 'short columns' or 'slender (long) columns' based on their slenderness ratio. The slenderness ratio is defined as the ratio of the effective length (le) to the least lateral dimension (D). According to IS 456:2000 (the Indian Standard code for Plain and Reinforced Concrete), a column is considered a short column if the ratio of its effective length to its least lateral dimension is less than 12. Conversely, if this ratio exceeds 12, the column is classified as a long or slender column. Long columns are susceptible to buckling, whereas short columns primarily fail due to crushing of the material. Therefore, the threshold value is 12.
The anti-siphonage pipe is not required in:
A)
One pipe system
B)
Two pipe system
C)
Single stack system
D)
Double stack system
In plumbing and drainage systems, an anti-siphonage pipe (or vent pipe) is used to prevent the siphoning of water seals in traps, which would otherwise allow foul gases from the sewer to enter the building.
1. **Single Stack System**: In this system, a single pipe carries both waste and soil. Because there is only one pipe, there is a high risk of pressure fluctuations causing siphonage; therefore, anti-siphonage pipes are often required to maintain trap seals.
2. **One Pipe and Two Pipe Systems**: These are traditional systems where waste and soil are handled separately or together, but they typically rely on additional venting (anti-siphonage) to ensure the traps are not sucked dry during high flow.
3. **Double Stack System**: This system consists of two separate stacks: one for soil (waste from WCs) and one for waste (from sinks, baths, etc.). The waste stack also acts as a vent for the soil stack. Because the system is designed with separate paths for air and water flow, the pressure remains balanced, and the risk of siphonage is naturally eliminated. Consequently, separate anti-siphonage pipes are not required in a double stack system.
Therefore, the double stack system is the only one among the options where anti-siphonage pipes are redundant.
The minimum vertical reinforcement in RCC tank shall be ___________ for deformed bars of the concrete area of the section under consideration.
A)
0.1 %
B)
0.25 %
C)
0.8 %
D)
1 %
In the design of reinforced concrete (RCC) water tanks, minimum reinforcement is provided to control cracking caused by temperature changes and shrinkage, as water-tightness is a critical requirement. According to standard codes of practice for liquid retaining structures (such as IS 3370), the minimum reinforcement for deformed bars (high-strength deformed bars) is specified to ensure structural integrity and crack control. For deformed bars, the minimum reinforcement is typically 0.25% of the cross-sectional area of the concrete. If smooth round bars were used, the requirement would be higher (typically 0.3%). Therefore, option (b) is the correct technical specification for deformed bars in RCC tanks.