Past Questions — 2026

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.

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.

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.

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.

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 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.

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.

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.

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.

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'.

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.

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').

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.

HDPE is a thermoplastic polymer produced from the monomer ethylene. In the context of piping materials for Public Health Engineering (PHE), it is widely used due to its high strength-to-density ratio, corrosion resistance, and flexibility. Breakdown of the acronym: - High Density: Refers to the molecular structure where there is minimal branching, allowing the polymer chains to pack closely together, increasing density and strength. - Poly: Short for polymer. - Ethylene: The chemical building block (monomer) used to create the plastic. Analysis of other options: - Option (a) 'Pipe Element' is incorrect as 'E' stands for Ethylene. - Option (b) 'Durable Pipe Equipment' is incorrect; while HDPE is durable, the acronym does not stand for this. - Option (d) 'Ductile Poly Element' is incorrect; 'Ductile' is a property often associated with cast iron (Ductile Iron), not the name of the HDPE polymer.

RCC stands for Reinforced Cement Concrete, which is concrete strengthened with steel reinforcement bars to improve tensile strength. Option c is correct. The other options are incorrect because 'Reinforced Clay Concrete' is not a standard construction term, 'Ready Cement Concrete' is not the meaning of RCC, and 'Rapid Cement Concrete' is also not a recognized expansion of RCC.

Rainwater harvesting collects and stores rainwater so it can be used directly or allowed to percolate into the ground, thereby increasing groundwater recharge. This is the main benefit of the practice. The other options are incorrect because rainwater harvesting does not waste water; it conserves it. It does not cause pollution; in fact, it can reduce runoff and contamination. It also does not promote corrosion; corrosion is unrelated to the purpose of harvesting rainwater.

The process of water treatment follows a specific sequence: Intake → Coagulation/Flocculation → Sedimentation → Filtration → Disinfection → Storage/Distribution. 1. **Service Reservoir (Correct):** This is the final structure in the treatment chain. Its primary purpose is to store treated (potable) water to balance the fluctuations in demand throughout the day and to maintain a constant pressure in the distribution network. 2. **Sedimentation tank (Incorrect):** This is a primary treatment unit where suspended particles settle at the bottom due to gravity before the water moves to filtration. 3. **Filter bed (Incorrect):** This is a treatment unit used to remove fine suspended particles and microorganisms from the water; it is a process of purification, not storage. 4. **Intake well (Incorrect):** This is the very first structure in a water supply system, used to draw raw (untreated) water from a source like a river or lake.

Safe Bearing Capacity (SBC) of soil is defined as the maximum intensity of pressure that can be applied to the soil such that the shear stress developed in the soil does not exceed the safe shear strength of the soil, and the settlement remains within permissible limits. Since it is a measure of 'pressure' or 'stress', it must be expressed in units of Force per unit Area. 1. Analysis of Options: - Option (a) m³: This is a unit of volume, not pressure. - Option (b) kg: This is a unit of mass, not pressure. - Option (c) kN/m²: This is a unit of pressure (Kilo-Newton per square meter), which is equivalent to the kilo-Pascal (kPa). This is the standard unit for bearing capacity. - Option (d) kN: This is a unit of force, not pressure. Therefore, the correct unit for expressing the safe bearing capacity of soil is kN/m².

Step-by-step reasoning: 1. Analysis of Brick Types: Bricks are categorized based on their manufacturing process and quality. Burnt clay bricks (First class, Second class, Engineering) undergo a firing process in a kiln, which gives them high compressive strength and durability. 2. Sun-dried Bricks: These are bricks that are molded and dried in the sun without being fired in a kiln. Because they are not burnt, they have very low strength, poor durability, and are highly susceptible to water damage. 3. Application: Due to their low cost and low strength, sun-dried bricks are unsuitable for permanent structures but are ideal for temporary constructions, such as temporary sheds, boundary walls for short-term use, or low-cost rural housing. 4. Evaluation of other options: (a) First class bricks are used for permanent, high-quality load-bearing structures. (b) Second class bricks are used for permanent structures where a plaster coat is applied. (d) Engineering bricks are high-density, low-absorbency bricks used for heavy-duty permanent works like sewers and bridge abutments.

In a telescope, the objective lens forms a real, inverted image of the distant object at its focal plane. For proper viewing and accurate focusing, this real image must coincide with the plane of the cross hairs (the diaphragm), so that the image and cross hairs are seen sharply together. The eye-piece then magnifies this image. Hence, the correct answer is the plane of cross hairs. The other options are incorrect because the image is not formed at the centre of the telescope, not at the optical centre of the eye-piece, and it cannot be anywhere inside the telescope.

Approximate cost = cubic content × rate per cubic metre = 400 × 180 = 72,000. Hence the correct answer is Rs. 72,000/-. The other options do not match this direct multiplication.

A sprinkler irrigation system gives the best results when water is distributed through revolving sprinkler heads. These heads rotate and spray water uniformly over the field, closely simulating natural rainfall. Nozzles alone are not the complete mounting arrangement, open pipes are not suitable for uniform sprinkler application, and pipes with holes near the crop describe a different, less efficient method.

In rubble masonry, stones should be hard so they can withstand weathering, loading, and dressing without breaking easily. Hard stones provide durability and strength to the masonry. 'Tough' is desirable in some contexts, but the standard requirement here is hardness. 'Heavy' and 'large' are not the main criteria for selecting stone for rubble masonry.

In estimation and costing, the formwork (shuttering) for concrete works is commonly taken as about 25% to 33% of the total cost of a concrete structure. That corresponds to 1/4 to 1/3 of the total cost. Since the options are written in descending fractions, option (b) best matches this standard rule of thumb. The other options either overstate or understate the usual proportion.

The probability of occurrence in any one year is the reciprocal of the return period. P = 1/T = 1/20 = 0.05 So, the correct answer is 0.05. - (b) 0.0008 is too small. - (c) 0.02 corresponds to a 50-year return period. - (d) 0.08 corresponds to a 12.5-year return period.