Past Questions — 2026

In road construction, stones used for aggregates (soling, WMM, and bituminous layers) must possess high compressive strength, high toughness, and resistance to wear and abrasion. 1. Basalt: This is an igneous rock known for its extreme hardness, density, and durability. It has high crushing strength and low water absorption, making it ideal for road surfaces and heavy-duty pavements where it must withstand constant traffic loads and weathering. 2. Marble: This is a metamorphic rock primarily used for ornamental and decorative purposes. It is too soft and susceptible to chemical weathering (acid rain) for road works. 3. Sandstone: While used in some building constructions, sandstone is generally too porous and lacks the necessary toughness and abrasion resistance required for high-traffic road surfaces. 4. Limestone: Although used in some road bases or as a filler, limestone is generally softer than basalt and can be prone to wear and chemical degradation over time compared to igneous rocks.

Step-by-step reasoning: 1. Definition of Footing: A footing is the lower part of a foundation that spreads the load of the structure over a larger area of soil to prevent shear failure or excessive settlement. 2. Analysis of Options: - Isolated Footing: This is a type of shallow foundation used to support a single column. It is the most economical and common choice when the soil bearing capacity is sufficient and columns are spaced far apart. - Combined Footing: This is used when two or more columns are so close together that their isolated footings would overlap, or when a column is near a property line. - Raft (Mat) Footing: This is a large continuous slab that supports all the columns and walls of a building, used when the soil is weak or the column loads are very high. - Pile Footing: This is a deep foundation used to transfer loads to a deeper, stronger soil layer or rock when the surface soil is incapable of supporting the load. 3. Conclusion: Since the question specifically asks for a footing provided for a 'single column', the correct answer is the Isolated footing.

Rainwater harvesting (RWH) is the process of collecting, filtering, and storing rainwater for future use or directing it into the ground to replenish aquifers. 1. Why 'b' is correct: The primary objective of RWH is to capture precipitation that would otherwise run off and allow it to infiltrate the soil, thereby raising the water table and recharging groundwater reserves. This is critical for sustainable water management, especially in regions facing water scarcity. 2. Why 'a' is incorrect: While RWH can reduce the volume of peak runoff during heavy rain, its primary purpose is water conservation and supply, not large-scale flood control (which typically requires dams, levees, and storm drains). 3. Why 'c' is incorrect: RWH aims to *decrease* surface runoff by capturing the water, not increase it. Increasing runoff leads to wastage of water and higher risks of flooding. 4. Why 'd' is incorrect: Soil erosion is caused by uncontrolled surface runoff washing away topsoil. RWH helps *prevent* soil erosion by reducing the velocity and volume of runoff, rather than promoting it.

Concrete is a composite material consisting of a binding medium and inert fillers. 1. **Cement (The Binder):** Cement is the active ingredient. When mixed with water, it undergoes a chemical reaction called hydration, forming calcium silicate hydrate (C-S-H) gel. This gel binds the aggregates together and provides the structural strength and hardness to the concrete. Therefore, cement is the primary source of strength. 2. **Water (The Activator):** Water is necessary to initiate the chemical reaction (hydration) and provide workability. However, excess water actually decreases the strength of concrete by increasing porosity (water-cement ratio principle). 3. **Sand (Fine Aggregate):** Sand acts as a filler that occupies the voids between coarse aggregates and reduces shrinkage. While it provides bulk and stability, it does not 'give' strength in the sense of binding the material together. 4. **Admixture (The Modifier):** Admixtures are chemicals added to modify specific properties (like setting time or workability). While some can enhance strength, they are not the primary ingredient responsible for the inherent strength of concrete.

Step-by-step reasoning: 1. The question asks for a disease spread through contaminated water, which is known as a 'water-borne disease'. 2. Analysis of options: - Malaria: Caused by Plasmodium parasites and spread via the bite of an infected female Anopheles mosquito (Vector-borne). - Dengue: Caused by the Dengue virus and spread via the bite of an infected Aedes aegypti mosquito (Vector-borne). - Cholera: Caused by the bacterium Vibrio cholerae. It is transmitted through the ingestion of contaminated water or food (Water-borne). - Tuberculosis: Caused by Mycobacterium tuberculosis and spread through the air via droplets when an infected person coughs or sneezes (Airborne). 3. Conclusion: Only Cholera is transmitted through contaminated water.

Step-by-step reasoning: 1. Analysis of Application: Drinking water supply systems require the movement of large volumes of water (high discharge) at moderate pressures to distribute water from reservoirs or wells to households. 2. Centrifugal Pumps: These are dynamic pressure pumps that use an impeller to add kinetic energy to the fluid. They are ideal for water supply because they handle high flow rates, have a simple design with few moving parts (reducing maintenance), and provide a continuous, non-pulsating flow. 3. Evaluation of other options: (a) Gear pumps are positive displacement pumps used primarily for high-viscosity fluids like oils, not water. (b) Reciprocating pumps provide high pressure but low discharge and create pulsating flow, making them inefficient for large-scale water distribution. (d) Jet pumps are typically used for shallow wells or specialized applications but cannot match the efficiency and scale of centrifugal pumps for general municipal water supply. Therefore, the centrifugal pump is the industry standard for drinking water supply systems.

Analysis of Rates is the process of calculating the cost of a particular unit of work (e.g., per cubic meter of concrete or per square meter of plastering). It involves calculating the quantities of materials required, the labor hours needed, the cost of machinery/tools, and adding overheads and contractor's profit to arrive at a final unit rate. Why other options are incorrect: - Option (a): The purpose of analysis is to find the actual cost, not necessarily to reduce it, although it helps in cost control. - Option (b): Profit is a component added during the analysis, but the primary goal of the entire process is not simply to 'increase profit'. - Option (d): Analysis of rates includes materials, plant, and machinery in addition to labor; it is not limited to labor only.

In civil engineering and building materials, it is crucial to distinguish between the 'Standard size' and the 'Nominal size' of a brick. 1. **Standard Size (Modular Size):** According to Bureau of Indian Standards (BIS), the standard or modular size of a burnt clay brick is 190 mm × 90 mm × 90 mm. This is the actual dimension of the brick without mortar. 2. **Nominal Size:** The nominal size includes the thickness of the mortar joint (usually 10 mm). Therefore, the nominal size is calculated as (190+10) × (90+10) × (90+10) = 200 mm × 100 mm × 100 mm. 3. **Traditional Size:** Option (d) 230 × 115 × 75 mm refers to the traditional size commonly used in older constructions in India, but it is not the 'Standard' modular size. Comparing the options: - Option (a) is incorrect as it does not match any standard specification. - Option (b) is the correct Standard/Modular size. - Option (c) is the Nominal size (Standard + Mortar). - Option (d) is the Traditional size.

A soak pit (also known as a seepage pit) is a covered, porous-walled chamber that allows treated wastewater (usually effluent from a septic tank) to slowly percolate or infiltrate into the surrounding soil. The soil acts as a natural filter, purifying the water as it moves downward. Why other options are incorrect: - a. Solid waste disposal: Solid waste is managed via landfills or incineration, not soak pits, as solids would clog the porous walls of the pit. - c. Stormwater storage: Stormwater is typically managed via drains, detention ponds, or rainwater harvesting systems. A soak pit is designed for low-volume, consistent wastewater flow, not the high-volume surges of stormwater. - d. Chemical disposal: Chemical waste requires specialized hazardous waste treatment; discharging chemicals into a soak pit would contaminate the groundwater and soil.

Storm water refers to surface runoff resulting from precipitation (rain or snowmelt). In civil engineering and urban planning, drainage systems are categorized based on the type of waste they carry: 1. Storm water drains (Option b) are specifically designed to collect and convey runoff from roads, rooftops, and open grounds to prevent flooding and waterlogging. 2. Sanitary sewers (Option a) are designed to carry domestic and industrial wastewater (sewage) from toilets, sinks, and showers to a treatment plant. Mixing storm water into sanitary sewers can lead to 'Combined Sewer Overflows' (CSOs), which can overwhelm treatment plants. 3. Septic tanks (Option c) are onsite wastewater treatment systems used for the primary treatment of sewage in areas without a centralized sewer system. 4. Soak pits (Option d) are porous-walled chambers that allow treated effluent or greywater to percolate into the ground; they are not used for the collection of large volumes of storm water runoff.

Step-by-step reasoning: 1. Concrete is a mixture of cement, aggregates, water, and inevitably, entrapped air. 2. Entrapped air voids reduce the density and strength of the concrete and increase permeability, which can lead to durability issues. 3. Compaction is the process of removing these entrapped air bubbles from the freshly placed concrete. This is typically achieved through mechanical vibration (using needle vibrators or plate vibrators) or manual tamping. 4. Analysis of other options: (a) Mixing is the process of combining ingredients to ensure a homogeneous distribution; while it incorporates air, it does not remove it. (b) Placing is the act of transporting and positioning the concrete in the formwork. (d) Curing is the process of maintaining moisture and temperature to allow the cement to hydrate and gain strength; it occurs after the concrete has set and does not remove air voids.

Step-by-step reasoning: 1. The question asks for a structure specifically used to lift groundwater 'manually'. 2. A 'Bore well' (a) and 'Tube well' (b) are general terms for the structure of the hole and casing; they require a lifting mechanism (like a submersible pump or a hand pump) to extract water. 3. A 'Dug well' (d) is a wide-diameter excavation where water is often lifted manually using a bucket and rope, but in the context of modern engineering and 'structures used to lift', the Hand Pump Tube Well is the specialized engineering structure designed specifically for manual suction/lifting. 4. A 'Hand Pump Tube Well' (c) combines the tube well structure with a manual pump mechanism, making it the most precise answer for a structure designed for manual extraction. While dug wells are manual, the term 'Hand Pump Tube Well' explicitly describes the mechanism of lifting integrated into the structure.

In water supply engineering, an intake structure is a hydraulic structure built at the source of water (such as a river, lake, or reservoir) to safely withdraw water and convey it to the water treatment plant. Step-by-step analysis of options: 1. Option (a) Storage: Storage is the primary function of reservoirs, tanks, or dams, not intake structures. While an intake is located at a storage source, its purpose is withdrawal, not storage. 2. Option (b) Collection of water from source: This is the correct definition. The intake structure is designed to collect water from the raw source while preventing debris, fish, and large floating materials from entering the pumping system. 3. Option (c) Treatment: Treatment occurs at the Water Treatment Plant (WTP) through processes like coagulation, sedimentation, and filtration. The intake structure only delivers raw water to the plant. 4. Option (d) Distribution: Distribution is the final stage of the water supply system, involving a network of pipes that deliver treated water to the end consumers.

In reservoir engineering, the primary goal is to store the maximum volume of water with the minimum expenditure on the dam structure. A valley with a narrow gorge is the ideal site because: 1. It allows for a shorter dam length (reducing construction costs) while creating a deep, wide storage area upstream. 2. Narrow gorges typically provide strong rock abutments, which are essential for the stability of the dam. 3. It minimizes the area of land submerged relative to the volume of water stored. Why other options are incorrect: - Flat land (a): Building a reservoir on flat land would require massive embankments (dykes) around the entire perimeter to hold water, making it economically unfeasible. - Hill top (c): While tanks can be built on hilltops for gravity distribution, a large-scale reservoir requires a natural basin to collect and store water; a hilltop is not a natural catchment basin. - Coastal plain (d): Coastal plains are generally flat and prone to saltwater intrusion or seepage, making them unsuitable for large-scale freshwater storage reservoirs.

Earthwork is measured by volume because excavation, filling, and embankment involve three-dimensional quantities. Therefore, it is generally taken in cubic meter (m³). The other options are incorrect: number is used for discrete items like manholes or poles, running meter is used for linear items like pipes or cables, and square meter is used for area-based work like plastering or flooring.

Bearing capacity refers to the capacity of soil to support the loads applied to the ground. This property is primarily governed by the soil's shear strength, particle size, and interlocking capabilities. 1. **Gravel (Option d):** Gravel consists of the largest particles among the given options. Due to the large grain size, gravel exhibits high internal friction and strong interlocking between particles, resulting in the highest shear strength and, consequently, the highest bearing capacity. 2. **Sand (Option c):** Sand also has good bearing capacity due to internal friction, but because the particles are smaller than gravel, the interlocking is less significant, making its bearing capacity generally lower than that of well-graded gravel. 3. **Silt (Option b):** Silt has smaller particles and lower internal friction than sand and gravel, leading to a lower bearing capacity. 4. **Clay (Option a):** Clay consists of very fine particles. Its bearing capacity is generally the lowest among these four, especially in saturated conditions, as it is prone to consolidation and settlement under load. Therefore, in order of decreasing bearing capacity: Gravel > Sand > Silt > Clay.

In construction, a binding material is a substance that holds other materials (like aggregates) together to form a solid, cohesive mass. 1. **Cement (Correct):** Cement is a hydraulic binder. When mixed with water, it undergoes a chemical reaction called hydration, forming a paste that binds sand and aggregates together to create concrete or mortar. It is the most common binding material used in modern civil engineering. 2. **Sand (Incorrect):** Sand is a 'fine aggregate'. It provides bulk and stability to the mix but does not have the chemical property to bind other materials together. 3. **Aggregate (Incorrect):** Aggregates (coarse or fine) are inert fillers that provide strength and volume to the structure. They are the materials being bound, not the binder itself. 4. **Bricks (Incorrect):** Bricks are masonry units. While they are the structural components of a wall, they require a binding material (like cement mortar) to be joined together.

Step-by-step reasoning: 1. **Sedimentation**: This is a physical water treatment process that uses gravity to remove suspended particles (solids) from water. Heavier particles settle to the bottom of a tank over time, forming a sludge layer, which is then removed. This is the primary unit designed specifically for the removal of suspended solids. 2. **Filtration (Option a)**: While filtration also removes particles, it is typically used as a secondary polishing step to remove *smaller* suspended particles and colloidal matter that did not settle during sedimentation. Sedimentation is the primary unit for bulk suspended particle removal. 3. **Disinfection (Option b)**: This is a chemical or physical process (e.g., chlorination, UV) used to kill or inactivate pathogenic microorganisms. It does not remove physical suspended particles. 4. **Aeration (Option d)**: This process involves bringing water and air into close contact to remove dissolved gases (like CO2 or H2S) and oxidize dissolved metals (like Iron and Manganese). It is not used for the removal of suspended particles. Therefore, Sedimentation is the most accurate answer for the unit that removes suspended particles via gravity.

The pH value of water is a measure of its acidity or alkalinity on a scale from 0 to 14, where 7 is neutral. For drinking water, the pH must be maintained within a specific range to ensure it is neither too corrosive nor too scale-forming. According to the World Health Organization (WHO) and the Bureau of Indian Standards (BIS) IS 10500:2012, the acceptable limit for pH in drinking water is 6.5 to 8.5. - Option (a) 5–6: This range is acidic. Acidic water can be corrosive to plumbing and distribution systems, leaching metals like lead and copper into the water. - Option (b) 6.5–8.5: This is the standard acceptable range that ensures water is chemically stable and palatable. - Option (c) 7–9: While mostly acceptable, the upper limit of 9 exceeds the standard guideline of 8.5. - Option (d) 8–10: This range is too alkaline, which can lead to a bitter taste and the formation of scale (calcium carbonate deposits) in pipes.

The water-cement (w/c) ratio is the ratio of the weight of water to the weight of cement used in a concrete mix. According to Abram's Law, the strength of concrete is primarily governed by the water-cement ratio. 1. Why 'Strength of concrete' is correct: A lower w/c ratio (within workable limits) results in a denser cement paste with fewer capillary pores, leading to higher compressive strength. Conversely, an increase in the w/c ratio increases the porosity of the hardened cement paste, which significantly reduces the strength and durability of the concrete. 2. Why other options are incorrect: - (a) Colour of concrete: The colour is primarily determined by the type of cement, the type of aggregates used, and the presence of admixtures, not the w/c ratio. - (b) Setting time only: While water content can influence the rate of hydration, setting time is more significantly affected by the chemical composition of the cement, temperature, and the use of accelerators or retarders. - (d) Cost: While the amount of cement used affects cost, the specific ratio of water to cement is a technical parameter for quality and strength rather than a primary driver of the overall project cost.

Solid waste segregation is the process of dividing waste into different groups (categories) based on their properties, such as biodegradable (wet waste), non-biodegradable (dry waste), hazardous waste, and recyclable materials. This is a critical first step in integrated waste management as it facilitates efficient recycling, composting, and safe disposal. Analysis of other options: - Option (a) Grinding waste: This refers to size reduction or shredding, which is a processing step, not segregation. - Option (c) Burning waste: This is known as incineration, which is a method of waste disposal/volume reduction. - Option (d) Transporting waste: This is the logistics/collection phase of waste management, moving waste from the source to a treatment or disposal site.

The Mizoram Water Supply (Control) Act is a piece of legislation specifically designed to govern the distribution, management, and safeguarding of water intended for human consumption. 1. Why Option (c) is correct: The primary objective of 'Water Supply (Control)' acts in state jurisdictions is to ensure that drinking water sources are protected from contamination, that the distribution is regulated to prevent wastage, and that the government has the authority to control the supply to ensure public health and safety. 2. Why Option (a) is incorrect: Irrigation is governed by separate irrigation acts or agricultural water management policies, as the technical and legal requirements for crop watering differ significantly from potable water supply. 3. Why Option (b) is incorrect: While industrial supply may be a component of water management, the 'Control Act' focuses on the broader public mandate of drinking water rather than specifically targeting industrial utility frameworks. 4. Why Option (d) is incorrect: Sewage regulation falls under 'Drainage' or 'Sanitation' acts (such as the Water (Prevention and Control of Pollution) Act), which deal with the disposal of waste rather than the supply of clean water.

Assam-type buildings are a traditional style of architecture prevalent in Northeast India, specifically designed to withstand the high seismic activity (earthquakes) and heavy rainfall of the region. The key characteristics of this style include: 1. Use of lightweight materials: The primary structural framework consists of timber or bamboo. 2. Flexible joints: The lightweight timber structure provides flexibility, which prevents the building from collapsing during an earthquake. 3. Wall construction: The walls are typically made of 'Ikra' (a type of reed) or bamboo mats plastered with mud or cement, rather than heavy masonry. 4. Sloping roofs: They feature steeply pitched roofs, usually covered with CGI (Corrugated Galvanized Iron) sheets, to drain heavy rainwater quickly. Comparing the options: - Option (a) Steel framed: While modern versions may use steel, the traditional and defining characteristic of 'Assam-type' is timber/bamboo. - Option (c) RCC framed: RCC (Reinforced Cement Concrete) is heavy and rigid; Assam-type buildings were specifically developed as an alternative to heavy masonry/concrete to reduce seismic risk. - Option (d) Masonry dome: This is characteristic of Indo-Islamic or classical architecture, not the regional vernacular style of Assam.

In hydraulics, a trapezoidal section is one of the most common cross-sections used for open channels (such as irrigation canals and drainage ditches). This is because a trapezoidal shape provides a balance between hydraulic efficiency and structural stability; the sloped sides prevent the banks from collapsing due to soil pressure and erosion, which would happen in a purely rectangular section. Why other options are incorrect: - a. Culverts: While some culverts can be trapezoidal, they are predominantly circular, box (rectangular), or arch-shaped to handle structural loads from the road above. - c. Pipelines: Pipelines are almost exclusively circular to withstand internal hydrostatic pressure uniformly (hoop stress). - d. Wells: Wells are typically circular to ensure structural integrity against external soil/water pressure and to facilitate drilling/sinking processes.

In the context of sanitation and public health engineering, 'Conservancy' (specifically the Conservancy System) refers to the method of removing human excreta (night soil) and refuse from premises manually or mechanically for disposal elsewhere, rather than using a water-borne sewerage system. - Option (a) Water supply refers to the provision of potable water to consumers. - Option (b) Night soil collection and disposal is the definition of a conservancy system, where waste is collected in pits or buckets and transported to a disposal site. - Option (c) Irrigation refers to the artificial application of water to land for agricultural purposes. - Option (d) Stormwater control refers to the management of runoff from rain and snow to prevent flooding and pollution.