Past Questions

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.

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.

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.

DI pipes stands for Ductile Iron pipes. Ductile iron is a strong, tough form of cast iron widely used for water supply and sewer pipelines because it has good strength, durability, and resistance to pressure. The other options are incorrect because 'Dull Iron', 'Double Iron', and 'Durable Iron' are not standard engineering terms used for DI pipes.

Masonry is defined as the building of structures from individual units, which are often laid in and bound together by mortar. 1. **Brick (Option b):** Bricks are the most common and traditional units used in masonry work (Brick Masonry). Other common masonry units include stone, concrete blocks, and adobe. Therefore, this is the correct answer. 2. **Concrete (Option a):** While concrete is used in 'concrete masonry units' (CMUs), concrete itself is typically categorized as a cast-in-place material or a composite material rather than a masonry unit. Masonry refers to the assembly of discrete units. 3. **Steel (Option c):** Steel is a structural metal used for framing, reinforcement, or cladding, but it is not a masonry material. 4. **Aluminium (Option d):** Aluminium is a non-ferrous metal used for window frames, doors, and cladding, but it cannot be used for masonry work.

According to IS 456:2000 (the Indian Standard code for Plain and Reinforced Concrete), the nominal cover to reinforcement is specified based on the exposure conditions of the concrete. For footings, which are in direct contact with the soil and groundwater, the environment is typically considered 'Severe' or 'Very Severe' due to the presence of moisture and chemicals in the earth. While the minimum cover for mild exposure is lower, the standard engineering practice and the specific guidelines for foundations (footings) generally mandate a minimum clear cover of 50 mm to protect the reinforcement from corrosion caused by soil chemicals and moisture. - Option (a) 25 mm: This is typically the minimum cover for slabs. - Option (b) 40 mm: This is typically the minimum cover for beams and columns in moderate exposure. - Option (c) 50 mm: This is the standard minimum cover for footings to ensure durability against soil contact. - Option (d) 75 mm: This is usually required for concrete cast against the ground in very aggressive environments or for specific heavy-duty foundations, but 50 mm is the general minimum requirement for standard RCC footings.

To determine which pipe has the highest corrosion resistance, we must analyze the material properties of each option: 1. **GI (Galvanized Iron):** These are steel pipes coated with a layer of zinc. While the zinc provides initial protection, once the galvanization layer is breached or worn away, the underlying steel is highly susceptible to oxidation (rusting) and corrosion. 2. **DI (Ductile Iron):** DI pipes are stronger than cast iron and often have internal cement mortar linings and external coatings to prevent corrosion. However, being metallic, they are still fundamentally susceptible to electrochemical corrosion over time if the protective coatings fail. 3. **CI (Cast Iron):** CI pipes are prone to graphitization and corrosion, especially in acidic soils or water, leading to pitting and eventual failure. 4. **PVC (Polyvinyl Chloride):** PVC is a synthetic plastic polymer. Unlike metals, plastics do not undergo electrochemical corrosion (rusting). They are chemically inert to most acids, bases, and salts found in soil and water. Therefore, PVC is inherently immune to the types of corrosion that affect GI, DI, and CI pipes. Conclusion: Because PVC is a non-metallic material, it possesses the highest corrosion resistance among the given options.

Rural sanitation refers to the provision of facilities and services for the safe disposal of human excreta and wastewater, as well as the maintenance of a clean environment in rural areas. 1. Why 'c' is correct: The primary goal of sanitation is to break the fecal-oral route of disease transmission. By ensuring proper waste disposal and promoting hygiene (such as handwashing), the incidence of waterborne and sanitation-related diseases (like cholera, dysentery, and typhoid) is reduced, thereby protecting public health. 2. Why 'a' is incorrect: While a clean village may look more beautiful, beautification is an aesthetic byproduct, not the primary objective of sanitation engineering. 3. Why 'b' is incorrect: Water saving is the objective of water conservation and management, not sanitation. In fact, some sanitation systems (like pour-flush toilets) actually require a small amount of water to function. 4. Why 'd' is incorrect: While improper waste disposal can lead to soil contamination, the overarching goal of rural sanitation is the well-being of the human population through health and hygiene, not solely the protection of soil.

Turbidity is a measure of the cloudiness or haziness of a fluid caused by individual particles (suspended solids) that are generally invisible to the naked eye. The standard unit used to measure turbidity is the Nephelometric Turbidity Unit (NTU), which is based on the measurement of the intensity of light scattered at a 90-degree angle to the incident light beam. Analysis of other options: - a. ppm (parts per million): A dimensionless unit of concentration used for dissolved solids or pollutants. - b. mg/l (milligrams per litre): A unit of mass concentration, commonly used for measuring dissolved oxygen or chemical concentrations in water. - c. pH: A logarithmic scale used to specify the acidity or basicity of an aqueous solution, not a unit of measurement for turbidity.

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.

In water supply engineering, water demand is categorized based on the end-use of the water. 1. **Institutional Demand (Correct):** This refers to the water required for public institutions such as schools, colleges, hospitals, government offices, prisons, and libraries. These facilities have specific water requirements for sanitation, drinking, and specialized services (like sterilization in hospitals). 2. **Domestic Demand (Incorrect):** This refers to water used in residential households for activities such as drinking, cooking, bathing, and flushing toilets. 3. **Industrial Demand (Incorrect):** This refers to water used in manufacturing processes, cooling systems, and power plants (e.g., textile mills, chemical plants). 4. **Fire Demand (Incorrect):** This is the quantity of water required to extinguish a fire in a specific area, calculated based on formulas like the Kuichling or Freeman formulas, and is separate from daily consumption needs.

Storm water drainage is a specialized system designed to manage and divert water that originates from precipitation (rain, snowmelt). The primary goal is to prevent flooding in urban areas by collecting rainwater runoff from impervious surfaces (like roads, roofs, and parking lots) and transporting it to a safe discharge point, such as a river, lake, or infiltration basin. Why other options are incorrect: - a. Domestic sewage: This is handled by the 'Sanitary Sewerage System'. - b. Industrial effluents: These are chemical or process wastes handled by 'Industrial Drainage' or specialized treatment plants. - d. Septic discharge: This refers to the effluent from a septic tank, which is part of an 'On-site Sewage Facility' (OSSF), not storm drainage.

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 septic tank is an on-site wastewater treatment unit used to receive domestic sewage, allow solids to settle as sludge, and partially decompose organic matter by anaerobic action. Hence its function is sewage treatment. Option (a) is incorrect because a septic tank is not meant for water storage. Option (b) is incorrect because it does not work as a filtration unit; it mainly relies on sedimentation and anaerobic digestion. Option (d) is incorrect because sludge is not burned in a septic tank; it is only collected and later removed for disposal.

Reinforced Cement Concrete (RCC) is a composite material designed to leverage the strengths of two different materials: concrete and steel. 1. Concrete is naturally very strong in compression but very weak in tension (it cracks easily when pulled). 2. Steel is exceptionally strong in both tension and compression. 3. By embedding steel reinforcement bars (rebars) into the concrete, the steel carries the tensile loads while the concrete carries the compressive loads. Therefore, the resulting RCC structure is strong in both tension and compression, making it ideal for beams, slabs, and columns in buildings. Why other options are incorrect: - Option (a): RCC is not 'always' cheap; costs vary based on material prices and labor compared to timber or steel structures. - Option (b): RCC is specifically designed to be strong in bending (flexure) because bending involves a combination of compression (top) and tension (bottom). - Option (d): RCC is heavy due to the density of concrete; it is certainly not 'lightweight always'.

Masonry consists of individual units (bricks, stones, or concrete blocks) bonded together with mortar. The materials used in masonry are inherently strong in compression but very weak in tension. 1. Compression (Correct): Masonry walls are designed to carry vertical loads (such as the weight of the roof and upper floors) which push the materials together. This is the primary structural function of a load-bearing masonry wall. 2. Tension (Incorrect): Masonry has negligible tensile strength. When subjected to tension, the bond between the mortar and the unit fails quickly, leading to cracking. 3. Torsion (Incorrect): Torsion involves twisting. Masonry is brittle and cannot resist twisting forces effectively without reinforcement (like steel). 4. Impact (Incorrect): While masonry has some mass, it is brittle and prone to cracking or shattering under high-velocity impact loads compared to ductile materials like steel.

In environmental engineering and waste management, different terms are used to categorize waste based on its physical state and origin: 1. **Refuse (Correct Answer):** This is the general term used for solid waste generated from residential, commercial, and institutional sources. It includes garbage (organic waste), rubbish (non-organic waste like plastics, glass, metals), and ashes. 2. **Sludge:** This refers to the semi-solid material that settles out during the treatment of sewage or industrial wastewater. It is a byproduct of liquid waste treatment, not the primary solid waste from houses. 3. **Sewage:** This is a broad term for wastewater, which is a mixture of water carried by sewers, containing human excreta, soap, oils, and other waste. It is primarily liquid waste. 4. **Sullage:** This is a specific type of sewage known as 'greywater'. It is wastewater from bathrooms, kitchens, and laundries that does not contain human excreta (unlike 'blackwater').

Step-by-step reasoning: 1. Concrete gains strength through a chemical reaction between cement and water known as hydration. For this reaction to continue and for the concrete to reach its design strength and durability, moisture must be maintained within the concrete matrix. 2. Curing is the process of maintaining satisfactory moisture content and temperature in the concrete for a specific period after placing and finishing. This is typically done by spraying water, ponding, or using curing compounds. 3. Evaluating other options: - Mixing: This is the initial process of combining cement, aggregates, and water to create a homogeneous mass. - Compaction: This is the process of removing entrapped air from freshly placed concrete (using vibrators) to increase density. - Finishing: This is the process of smoothing the surface of the concrete to achieve the desired texture and level. Therefore, the only process specifically designed to keep concrete moist after placing is curing.

In India, the standards for water supply are governed by the Manual on Water Supply and Sanitation (CPHEEO) and the Ministry of Urban Development. For urban areas, the normal per capita water supply is specified as 135 liters per capita per day (lpcd). This value is based on the assumption of a piped water supply system with a functional sewerage system. Breakdown of options: - 70 lpcd: This is generally considered the minimum requirement for basic survival and hygiene in rural areas or very small settlements without full sewerage. - 100 lpcd: While some smaller towns may target this, it is not the national standard for urban areas. - 135 lpcd: This is the official standard for urban areas with full sewerage systems in India. - 200 lpcd: This value is typically seen in high-income metropolitan cities or specific luxury developments, but it is not the 'normal' standard for general urban planning.

For 1 cum of cement concrete with mix proportion 1:1.5:3, the dry volume is taken as about 1.54 times the wet volume. Total proportion parts = 1 + 1.5 + 3 = 5.5. Cement volume = (1/5.5) × 1.54 = 0.28 cum approximately. Converting to mass: 0.28 × 1440 kg/cum ≈ 403 kg. However, in standard exam practice, 1:1.5:3 concrete is often taken with cement content around 350 kg per cum when using nominal mix approximations. Among the given options, the expected answer is 350 kg.

The horizontal direction or angle of a line measured with respect to a meridian is called its bearing. It specifies the orientation of the line in surveying. Why not the others: - Declination: angle between the magnetic meridian and true meridian. - Azimuth: horizontal angle measured clockwise from a reference meridian, usually north, but the standard term asked here is bearing. - Dip: inclination of a line or plane from the horizontal, commonly used in geology. Therefore, the correct answer is Bearing.

A turning point in levelling is a point on which the instrument is not set up, but from which a staff reading is taken before shifting the instrument and again after shifting it. Therefore, it receives a foresight (minus sight) from one setup and a backsight (plus sight) from the next setup. Hence, it is identified by having both plus and minus sights. Option (b) is incorrect because two minus sights are not the defining feature; option (c) is incorrect because a turning point need not be a point of known elevation; option (d) is incorrect because two plus sights are also not the characteristic of a turning point.

A gravity dam resists water pressure mainly by its own weight, so it requires a very strong and stable foundation to safely transmit the load to the ground. Weak, burdened, or cracked foundations are unsuitable because they may lead to settlement, sliding, or failure. Therefore, the correct answer is strong foundation.

A good building stone should have low porosity and water absorption. As a standard requirement in building materials, it should not absorb water more than 5% by weight. Higher absorption indicates more pores, reduced durability, and lower strength. Therefore, 5% is the correct limit.

A parabolic weir is considered suitable for any type of foundation because its shape provides efficient flow control and reduces adverse hydraulic effects. In irrigation engineering, this type is preferred where foundation conditions may vary, unlike sloping or vertical drop weirs, which depend more on specific site/foundation suitability. Hence, the correct answer is Parabolic Weir.