Correct Answer: threshold number
Explanation: Odour is measured in terms of the threshold number, indicating the sensitivity of the human nose to detect odours.
Correct Answer: osmoscope
Explanation: The odour of water is determined using an osmoscope.
Correct Answer: odour of water
Explanation: Goaty water refers to water with an unpleasant odour.
Correct Answer: colloidal solids
Explanation: The true colour of water is primarily due to the presence of colloidal solids.
Correct Answer: tintometer
Explanation: The colour of water is measured on the platinum cobalt scale using a tintometer.
Correct Answer: organic debris
Explanation: The color in water is often due to the presence of organic debris, including decomposing plant material and other organic substances.
Correct Answer: no colour
Explanation: The purest water tends to have no color, appearing transparent without any noticeable coloration.
Correct Answer: unaesthetic
Explanation: Highly colored waters are considered unaesthetic, meaning they are not visually appealing.
Correct Answer: 10^-3 to 10^-6 mm
Explanation: Colloidal particles in water typically have sizes ranging from 10^-3 to 10^-6 mm.
Correct Answer: is unaesthetic
Explanation: Turbidity makes water unaesthetic as it appears cloudy or turbid, affecting its visual appeal.
Correct Answer: standard silica scale
Explanation: Turbidity is measured using a standard silica scale, quantifying the cloudiness of water based on the concentration of suspended particles.
Correct Answer: suspended solids and colloidal solids
Explanation: Turbidity depends on the presence of suspended solids and colloidal solids in water.
Correct Answer: scatter light
Explanation: Turbidity is the ability of water to scatter light due to the presence of particles.
Correct Answer: intensity of light scattered when light is passed through
Explanation: Turbidity is measured by assessing the intensity of light scattered as it passes through a water sample.
Correct Answer: concentration and density of suspended and colloidal solids
Explanation: Turbidity of a water sample depends on the concentration and density of suspended and colloidal solids.
Correct Answer: Nephelometric Turbidity Unit (NTU)
Explanation: Turbidity is measured in NTU, which quantifies the cloudiness of water.
Correct Answer: affects photosynthesis of aquatic life
Explanation: Turbidity is undesirable as it can adversely affect the photosynthesis of aquatic life by reducing light penetration in water.
Correct Answer: coagulation and filtration
Explanation: Turbidity can be removed by employing coagulation and filtration techniques.
Correct Answer: all of the above
Explanation: Different turbidity meters such as Baylis, Hellige, and Jackson are suitable for measuring turbidity across various ranges.
Correct Answer: all of the above
Explanation: The pH of sewage can indicate its acidity, alkalinity, or neutrality. If pH < 7, sewage is acidic; if pH > 7, sewage is alkaline; and if pH = 7, sewage is neutral.
Correct Answer: boilers
Explanation: Absolutely soft water is crucial for boilers as hard water can lead to the formation of scale, reducing the efficiency of the boiler. Scale is formed due to the precipitation of minerals present in hard water.
Correct Answer: lead
Explanation: Lead is considered the most dangerous metal for human health. Exposure to lead can lead to various health issues, especially affecting the nervous system.
Correct Answer: 6.5 to 8.5
Explanation: The pH value of water for water supply is typically maintained in the range of 6.5 to 8.5. This range is considered suitable for human consumption and prevents corrosion in pipes.
Correct Answer: very good indicator of pathogenic bacteria
Explanation: B-coli (coliform bacteria) tests are conducted as they serve as a very good indicator of the presence of pathogenic bacteria. Their presence indicates potential contamination from fecal matter.
Correct Answer: lactose broth
Explanation: In a presumptive test for B-coli, a lactose broth is commonly used as the culture medium. The presence of coliform bacteria can be detected through the fermentation of lactose.
Correct Answer: nil
Explanation: The Biological Oxygen Demand (BOD) in domestic water should ideally be nil. BOD measures the amount of dissolved oxygen consumed by microorganisms in the water, indicating its organic pollution level.
Correct Answer: facultative bacteria
Explanation: Facultative bacteria can survive with or without oxygen. They have the ability to adapt to different environmental conditions.
Correct Answer: killing of diseases bacteria
Explanation: Disinfection of water involves the killing of disease-causing bacteria and microorganisms to make the water safe for consumption.
Correct Answer: increases with the temperature of water
Explanation: The efficiency of chlorination as a disinfection method increases with the temperature of water. Warmer water enhances the effectiveness of chlorine in killing bacteria.
Correct Answer: zinc
Explanation: Zinc is a heavy metal that generally has non-toxic properties. It is an essential mineral for the human body and is not considered harmful in moderate amounts.
Correct Answer: eliminating all life
Explanation: Sterilization is the process of eliminating all forms of life, including bacteria, viruses, and other microorganisms.
Correct Answer: CaOCl2
Explanation: The chemical formula of bleaching powder is CaOCl2. It is used as a disinfectant and for bleaching purposes.
Correct Answer: all of the above
Explanation: Aeration of water is done to achieve multiple purposes, including removing carbon dioxide, improving taste and odor, and increasing the oxygen content in the water.
Correct Answer: all of the above
Explanation: Aeration of water can be accomplished through various methods, including the use of spray nozzles, cascading, and trickling beds.
Correct Answer: sulphur-reducing bacteria
Explanation: Tuberculation in a metal pipe is caused by the activity of sulphur-reducing bacteria. These bacteria contribute to the formation of deposits and corrosion in the pipe.
Correct Answer: acidic
Explanation: The presence of algae in water indicates that the water is acidic. Algae thrive in environments with lower pH levels.
Correct Answer: acidity of water
Explanation: Alum, when added as a coagulant, increases the acidity of water. It is commonly used in water treatment processes.
Correct Answer: decreases
Explanation: When alum is mixed with water as a coagulant, it tends to decrease the pH value of water. This is important in the coagulation and flocculation processes.
Correct Answer: chemosynthesis
Explanation: The process of obtaining energy for bacterial synthesis through the oxidation of organic or inorganic matter is called chemosynthesis.
Correct Answer: suspended impurities
Explanation: Groundwater is generally free from suspended impurities, as these impurities are usually filtered out as water percolates through the soil.
Correct Answer: bitter taste
Explanation: An excess concentration of sodium salts in water can cause a bitter taste. This is often undesirable for drinking water.
Correct Answer: laxative effect
Explanation: An excess concentration of magnesium salts in water can have a laxative effect on individuals consuming the water.
Correct Answer: up to 3 ppm
Explanation: The maximum allowable amount of copper in domestic water is typically up to 3 ppm to ensure it meets health and safety standards.
Correct Answer: stains on clothes
Explanation: Iron in water can cause stains on clothes due to its ability to oxidize and form insoluble iron compounds.
Correct Answer: plumbo solvency
Explanation: Lead in water can cause plumbo solvency, where lead dissolves into the water. This is a concern due to the health risks associated with lead exposure.
Correct Answer: calorimetric test
Explanation: Iron and manganese levels in water are often estimated using a calorimetric test, which measures the color changes associated with these elements.
Correct Answer: base exchange process
Explanation: Water of zero hardness can be obtained through the base exchange process, which involves the removal of calcium and magnesium ions responsible for water hardness.
Correct Answer: 3 times the average demand
Explanation: Main pipes in water supply systems are typically designed to carry three times the average demand to ensure sufficient capacity during peak usage periods.
Correct Answer: 2 times the average demand
Explanation: Service pipes in water supply systems are generally designed to carry two times the average demand to meet the needs of consumers.
Correct Answer: 1.0 m/sec
Explanation: The velocity of flow in a 1 m cast iron pipe carrying a discharge of 0.785 cum/sec can be calculated using the formula velocity = discharge area. In this case, the velocity is approximately 1.0 m/sec.
Correct Answer: 30 cm
Explanation: The approximate diameter of the water mains can be determined based on the flow rate and velocity using hydraulic principles. In this case, a diameter of 30 cm is suitable for supplying the specified flow with the given velocity.
Correct Answer: 1:800
Explanation: Manning’s formula relates the hydraulic gradient, roughness coefficient (n), cross-sectional area, and wetted perimeter. With the given parameters and using Manning’s formula, the hydraulic gradient is calculated to be 1:800.
Correct Answer: 85%
Explanation: The coverage of water supply in Nepal, as per the census of 2011, is reported to be 85%. This indicates the percentage of the population with access to a reliable water supply.
Correct Answer: longitudinal temperature stress
Explanation: A pressure conduit laid underground may not be subjected to significant longitudinal temperature stress. It primarily deals with internal pressure, external loads, and other factors.
Correct Answer: D = 0.97 to 1.22 √Q
Explanation: According to Lea’s formula, the economical diameter of the pipe (D) is related to the discharge (Q). The formula suggests that D should be in the range of 0.97 to 1.22 times the square root of Q.
Correct Answer: all of the above
Explanation: If the diameter of the main pipe is taken less than the economical diameter, it can result in higher head loss, reduced efficiency, lower carrying capacity, and increased pumping costs.
Correct Answer: d.p / 2t
Explanation: The hoop stress in a pressure conduit is calculated using the formula d.p / 2t, where P is the total internal pressure, d is the diameter, and t is the thickness of the conduit.
Correct Answer: Pt = 3H3P / 2πz5
Explanation: The Boussinesq formula for evaluating the superimposed load transmitted to a pipe is given by Pt = 3H3P / 2πz5, where P is the load, Z is the slant height, H is the top of the pipe, and z is the considered point’s height.
Correct Answer: all of the above
Explanation: Thrust blocks are installed wherever there is a change in the direction or size of the pipeline, a change in the pressure line diagram, or where the pipeline ends at a dead end. They help resist the thrust generated by fluid pressure.
Correct Answer: Manning
Explanation: The formula v=1/n (r2/3s1/2) is associated with Manning’s formula, which relates the velocity (v) of flow in an open channel to the roughness coefficient (n), hydraulic radius (r), and slope (s).
Correct Answer: 10 m
Explanation: The Hydraulic Grade Line (HGL) should always be maintained above the Ground Level (GL) by a certain margin to ensure proper flow and pressure in the water supply system. A margin of 10 m is recommended in this context.
Correct Answer: zero and zero
Explanation: The pressure at the inlet and outlet in a break pressure tank is maintained at zero. Break pressure tanks are designed to absorb excess pressure during pump shutdown, preventing water hammer and other issues.
Correct Answer: below 1.8 m/sec
Explanation: The velocity of water in water mains with a diameter of 40 cm is usually kept below 1.8 m/sec to minimize frictional losses, control water hammer, and ensure efficient water transportation.
Correct Answer: all of the above
Explanation: The selection of material for a pipe depends on various factors, including the carrying capacity, durability, life expectancy, and the potential effect of the conveyed water on the pipe material.
Correct Answer: all of the above
Explanation: Gravity conduits can take various forms, including open channels, conduits (pipes), and tunnels. These structures are designed to allow the flow of water under the influence of gravity.
Correct Answer: all of the above
Explanation: Gravity conduits are structures that carry water under the influence of gravity, following the hydraulic gradient line. They can include various forms such as open channels, aqueducts, flumes, conduits, and tunnels.
Correct Answer: flume
Explanation: The open channels supported above the ground over trestles are called flumes. Flumes are structures designed to convey water, typically in an open channel supported on raised supports or trestles.
Correct Answer: rectangular
Explanation: The most commonly used section in a grade aqueduct is rectangular. The choice of section depends on various factors, including hydraulic efficiency and construction considerations.
Correct Answer: full
Explanation: Grade aqueducts are not allowed to run one-fourth full or half; they are designed to operate at full capacity. Running at full capacity ensures proper hydraulic performance.
Correct Answer: all of the above
Explanation: A circular gravity aqueduct is preferred due to its maximum hydraulic mean depth, maximum area per unit of wetted perimeter, and the potential for a cost-effective construction.
Correct Answer: all of the above
Explanation: Pressure conduits have advantages such as flow independence from the grade of the hydraulic grade line, economical construction due to a shorter path, and less chance of water pollution as they are closed systems.
Correct Answer: vee section
Explanation: Aqueducts are generally not designed in a vee section. The section chosen for an aqueduct depends on hydraulic considerations and construction requirements, and vee sections are not commonly used.
Correct Answer: vertically
Explanation: Asbestos cement pipes are generally laid vertically. The choice of laying position depends on the material properties and design considerations.
Correct Answer: asbestos cement
Explanation: Asbestos cement pipes are types of pipes that are generally laid vertically due to their relatively low strength compared to other materials.
Correct Answer: cast iron
Explanation: Cast iron is a commonly used material for water supply pipes that possesses properties of being not easily corroded, strong, having a long life, but being heavy and brittle.
Correct Answer: stronger
Explanation: As compared to cast iron pipes, steel pipes are generally stronger. However, they may also be heavier and costlier depending on specific characteristics.
Correct Answer: 550
Explanation: A nominal internal diameter of 550 mm for a cast iron (spun) pipe is incorrect. Standard sizes for cast iron pipes typically include diameters such as 300 mm, 400 mm, and 500 mm.
Correct Answer: all of the above
Explanation: Steel pipes are generally laid underground, can be connected by riveted or welded joints, and are suitable for withstanding high internal pressure.
Correct Answer: light in weight and easy to transport
Explanation: Asbestos pipes are light in weight and easy to transport. While they have other properties, such as resistance to corrosion, their use has declined due to health and environmental concerns associated with asbestos.
Correct Answer: 100 m head of water
Explanation: PVC pipes can withstand pressure up to 100 m head of water. PVC pipes are known for their durability, corrosion resistance, and ability to handle various levels of water pressure.
Correct Answer: GI
Explanation: If the head of water is more than 100 m, the type of pipe commonly used is GI (Galvanized Iron) due to its strength and durability under high pressure.
Correct Answer: all of the above
Explanation: The correct specifications for High-Density Polyethylene (HDP) pipe grades are as follows: – Grade II: 2.5 kg/cm2 – Grade III: 4 kg/cm2 – Grade IV: 6 kg/cm2
Correct Answer: all of the above
Explanation: Copper pipes are highly resistant to acidic and alkaline water, easy to bend, and do not sag when used for hot water supply. They are also not liable to corrosion.
Correct Answer: galvanized pipes
Explanation: Service connections to consumer houses are generally provided with galvanized pipes due to their corrosion resistance and durability.
Correct Answer: zinc
Explanation: A G.I. (Galvanized Iron) pipe has a coating of zinc, which helps protect the iron from corrosion.
Correct Answer: all of the above
Explanation: Sluice valves in main water supplies are used to regulate the flow, spaced about 5 km apart, and are generally provided at the summits.
Correct Answer: all of the above
Explanation: Pressure relief valves are provided in the water main to reduce pressure and are typically located upstream of the sluice valve or at the low point.
Correct Answer: both (a) and (b) of the above
Explanation: Air inlet valves are provided in water mains at both the summit of the pipe and downstream of the sluice valve to allow the release of trapped air and maintain proper operation.
Correct Answer: blow-off valve
Explanation: The valve provided at low points of the pipe to drain off water quickly under gravity is a blow-off valve.
Correct Answer: reflux valve
Explanation: The valve which allows water to flow in one direction but prevents its flow in the reverse direction is a reflux valve.
Correct Answer: at very depression and dead ends to drain out the waste water that may collect there
Explanation: Scour valves are provided at every depression and dead end to drain out the waste water that may collect there and prevent the accumulation of sediments.
Correct Answer: air valve
Explanation: Poppet valve is a type of air valve used in water systems.
Correct Answer: reflux valve
Explanation: The valve provided on the suction pipe in a tube-well is a reflux valve.
Correct Answer: hydraulic ram
Explanation: Impetus valve or waste valve is provided in a hydraulic ram.
Correct Answer: the increase of pressure after a certain limit
Explanation: Pressure relief valve is provided to prevent the increase of pressure beyond a certain limit in the system.
Correct Answer: reflux valve
Explanation: The valve provided after the pump in the rising mains to prevent the backflow of water when the pump is stopped is called a reflux valve. It ensures that water does not flow back into the pump when it is not in operation.
Correct Answer: decreases
Explanation: With the increase in the size of the water pipe, the permissible velocity decreases, assuming the discharge remains constant. Larger pipes are designed to accommodate a lower velocity to minimize frictional losses.
Correct Answer: butt welding
Explanation: High-Density Polyethylene (HDP) pipes are typically joined using butt welding, which involves connecting the plain ends of the pipes by heating and melting them together.
Correct Answer: solvent welding
Explanation: Plastic pipes are often joined using solvent welding, where a solvent is applied to the joint surfaces, causing them to soften and fuse together.
Correct Answer: simplex joint
Explanation: Asbestos pipes are commonly joined using a simplex joint, a type of joint where one pipe has a plain end (spigot), and the other has a socket into which the spigot is inserted.
FAQs on Water Supply & Sanitation Engineering MCQs for Civil Engineers
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