McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Civil Engineering .
| 101. |
In which unit operation, gases are released or absorbed in the water? |
| A. | gas transfer |
| B. | ion transfer |
| C. | solute stabilization |
| D. | solids transfer |
| Answer» A. gas transfer | |
| Explanation: in gas transfer, gases are released or absorbed in water by exposing the water through aeration under normal, increased or reduced pressure. | |
| 102. |
How many types of aerators are commonly used in the treatment of water? |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| Answer» C. 4 | |
| Explanation: there are 4 types of aerators namely gravity aerators, spray aerators, diffusers and mechanical aerators. | |
| 103. |
Which of the following process is used to remove the colloidal particles from water? |
| A. | chemical precipitation |
| B. | chemical coagulation |
| C. | ion exchange |
| D. | adsorption |
| Answer» B. chemical coagulation | |
| Explanation: chemical coagulation is used to remove colloidal particles by the use of coagulants which increase the particle size and they settle down. | |
| 104. |
Flocculation of iron from water by the addition of lime is an example of which of the following process? |
| A. | chemical precipitation |
| B. | chemical coagulation |
| C. | ion exchange |
| D. | adsorption |
| Answer» A. chemical precipitation | |
| Explanation: chemical precipitation removes the dissolved substance from water through ion transfer where precipitation of dissolved impurities takes place. | |
| 105. |
In which unit operation objectionable solutes are converted into unobjectionable forms without removal? |
| A. | gas transfer |
| B. | ion transfer |
| C. | solute stabilization |
| D. | solids transfer |
| Answer» C. solute stabilization | |
| Explanation: in solute stabilization, water is stabilized by chlorination or liming so that objectionable solutes are converted into unobjectionable form. | |
| 106. |
In which form of solute stabilization, hydrogen sulfide in water is oxidized into sulfate? |
| A. | chlorination |
| B. | liming |
| C. | re-carbonation |
| D. | super-chlorination |
| Answer» A. chlorination | |
| Explanation: by the process of chlorination, water gets stabilized by the conversion of hydrogen sulfide into sulfate. | |
| 107. |
Which form of solute stabilization occurs when water passes through limestone? |
| A. | chlorination |
| B. | liming |
| C. | re-carbonation |
| D. | super-chlorination |
| Answer» B. liming | |
| Explanation: when water passes through limestone, carbon dioxide in excess get converted into soluble bicarbonate. | |
| 108. |
In which process, excess lime is converted into bicarbonate? |
| A. | chlorination |
| B. | liming |
| C. | re-carbonation |
| D. | super-chlorination |
| Answer» C. re-carbonation | |
| Explanation: by re-carbonation of water softened by excess lime treatment, excess lime is converted into bicarbonate. | |
| 109. |
By which process, odour producing substances is oxidized? |
| A. | chlorination |
| B. | liming |
| C. | re-carbonation |
| D. | super-chlorination |
| Answer» D. super-chlorination | |
| Explanation: by addition of chlorine dioxide to water, odour producing substances are oxidized. | |
| 110. |
Solids are removed from the water by which of the following unit operation? |
| A. | inter facial contact |
| B. | solid stabilization |
| C. | ion transfer |
| D. | solids transfer |
| Answer» D. solids transfer | |
| Explanation: during solids transfer, solids are removed from water by straining, sedimentation, flotation and filtration. | |
| 111. |
Dealkalization results in removal of all the ions from the water. |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: dealkalization results in | |
| 112. |
Organic contaminants are removed from the water by the process of |
| A. | water softening |
| B. | demineralization |
| C. | absorption |
| D. | adsorption |
| Answer» D. adsorption | |
| Explanation: organic contaminants are removed from the water by the attraction and accumulation of one substance on the surface of another. | |
| 113. |
is an operation designed to force agitation in the fluid and induce coagulation. |
| A. | sedimentation |
| B. | flocculation |
| C. | disinfection |
| D. | aeration |
| Answer» B. flocculation | |
| Explanation: flocculation is an agitating process in which destabilized particles are brought into contact to promote agglomeration. | |
| 114. |
What is the dimension formula of mean velocity gradient? |
| A. | 1/t |
| B. | 1/t2 |
| C. | t |
| D. | t2 |
| Answer» A. 1/t | |
| Explanation: mean velocity gradient is expressed in metre per second/m or sec-1, so it has dimension formula of 1/t. | |
| 115. |
What is the normal value of the detention period adopted in a flocculator for design purpose? |
| A. | 30min |
| B. | 60min |
| C. | 90min |
| D. | 100min |
| Answer» A. 30min | |
| Explanation: the detention period in a flocculator for design purpose should be in the range of 10-40min and its normal value should be 30min. | |
| 116. |
The design value of the velocity of flow in a flocculator is |
| A. | 0.2-0.8m/s |
| B. | 0.3-0.5m/s |
| C. | 0.6-0.8m/s |
| D. | 0.1-0.5m/s |
| Answer» A. 0.2-0.8m/s | |
| Explanation: the normal value of the velocity of flow in a flocculator is 0.4m/s and its range is 0.2-0.8m/s. | |
| 117. |
What is the detention period of a clarifier used in the treatment of water? |
| A. | 1hour |
| B. | 2hours |
| C. | 3hours |
| D. | 4hours |
| Answer» C. 3hours | |
| Explanation: the detention period of a clarifier is lower than in the plain sedimentation tank and its range is 2.5 to 3 hours. | |
| 118. |
The pulsator clarifier is a type of |
| A. | horizontal flow sludge tank |
| B. | vertical flow sludge tank |
| C. | circular sludge tank |
| D. | plain sedimentation tank |
| Answer» B. vertical flow sludge tank | |
| Explanation: the pulsator clarifier is a vertical flow sludge tank in which pulse is generated at interval of 30sec to give rapid flow for 5-10sec resulting in the alternative rising up of the sludge blanket. | |
| 119. |
Which device solved the problem of unstable hydraulic conditions and operation of sludge removal equipment? |
| A. | centrifugal pump |
| B. | pulsator clarifier |
| C. | tube settler |
| D. | flocculator |
| Answer» C. tube settler | |
| Explanation: tube settler solved the problem of unstable hydraulic conditions and operation of sludge removal equipment by providing laminar flow conditions for sedimentation. | |
| 120. |
In which device, the primary mixing is followed by a secondary reaction zone resulting in formation of sludge blanket? |
| A. | centrifugal pump |
| B. | flocculator |
| C. | tube settler |
| D. | solid contact clarifier |
| Answer» D. solid contact clarifier | |
| Explanation: in solid contact clarifier, sludge blanket is formed where straining action occurs to remove some of the finer particles. the thickness of the blanket is 1m. | |
| 121. |
In which type of tube settler, tubes are slightly inclined in the direction of normal flow? |
| A. | solid contact clarifier |
| B. | steeply inclined tube settler |
| C. | vertical tube settler |
| D. | horizontal tube settler |
| Answer» D. horizontal tube settler | |
| Explanation: in horizontal tube settler, the tubes are slightly inclined in the direction of normal flow and the sludge settled is drained by filter backwash.they are used in small plants. | |
| 122. |
Ion exchange units are known as |
| A. | water hardeners |
| B. | water softeners |
| C. | water purifiers |
| D. | exchangers |
| Answer» B. water softeners | |
| Explanation: ion exchange units that replace calcium and magnesium ions from water are known as water softeners. they may also remove varying amounts of other inorganic pollutants such as metals. | |
| 123. |
Water softener units work most efficiently with particulate water. |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: water softener units work most efficiently with particulate-free water. ion exchange units that replace calcium and magnesium ions from water are known as water softeners. | |
| 124. |
Which of these have a negative electrical charge? |
| A. | calcium |
| B. | magnesium |
| C. | sodium |
| D. | chloride |
| Answer» D. chloride | |
| Explanation: calcium and magnesium ions are atoms having a positive electrical charge, as do sodium and potassium ions. ions of the same charge can be exchanged. | |
| 125. |
The ions with opposite charge can be exchanged. |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: ions of the same charge can be exchanged. in the process, the water containing calcium and magnesium ions is | |
| 126. |
While designing the demineralisation plant what is considered as the weak acidic cation load? |
| A. | alkaline hardness |
| B. | alkaline hardness+ ema |
| C. | ema |
| D. | silica |
| Answer» A. alkaline hardness | |
| Explanation: the load for weak acid cation is alkaline hardness alone. alkalinity is expressed as phenolphthalein alkalinity. it is also expressed as methyl orange alkalinity. | |
| 127. |
While designing the demineralisation plant what is considered as the strong acidic cation load? |
| A. | alkaline hardness |
| B. | alkaline hardness + ema |
| C. | ema |
| D. | silica |
| Answer» B. alkaline hardness + ema | |
| Explanation: the load for weak acid cation is alkaline hardness alone. this is also equivalent to total anions. total anions is equivalent to alkaline hardness + ema. | |
| 128. |
While designing the demineralisation plant what is considered as the strong basic anion load? |
| A. | alkaline hardness |
| B. | alkaline hardness + ema+co2 |
| C. | ema+silica |
| D. | silica+co2+ alkalinity+ema |
| Answer» D. silica+co2+ alkalinity+ema | |
| Explanation: the load for strong basic anion is silica+co2+ alkalinity+ema. this is in the case where there is no degasser. | |
| 129. |
While designing the demineralisation plant what is considered as the weak basic anion load? |
| A. | alkaline hardness |
| B. | alkaline hardness + ema |
| C. | ema |
| D. | silica |
| Answer» C. ema | |
| Explanation: the load for weak basic anion is ema alone. ema constitutes of chlorides, sulphides, nitrates etc. it is the sum total of these ions. | |
| 130. |
When is strong basic anion not necessary? |
| A. | silica is nil |
| B. | co2 is nil |
| C. | fluroine is nil |
| D. | sulphate is nil |
| Answer» A. silica is nil | |
| Explanation: when silica is nil, there is no requirement of a strong basic anion. degasser removes co2. a degasser tower is used in such cases. | |
| 131. |
When the hardness and alkalinity are around 30% what should be used? |
| A. | sac |
| B. | wac |
| C. | wac, sac |
| D. | wac, sac, wba |
| Answer» C. wac, sac | |
| Explanation: when the hardness and alkalinity are around 30%, then wac and sac should be used. wac removes temporary hardness caused by alkalinity. sac removes ema and alkalinity. | |
| 132. |
In case along with silica, there is high content in sulphide and chloride what should be used? |
| A. | wba |
| B. | wba and sba |
| C. | sba |
| D. | sba,wba and wac |
| Answer» B. wba and sba | |
| Explanation: in case the sulphide and chloride are present then wba should be used. sba removes only silica and alkalinity. it doesn’t remove ema. | |
| 133. |
What is the preferred regenerant in case of cation exchanger? |
| A. | hcl |
| B. | h2so4 |
| C. | h2co3 |
| D. | hf |
| Answer» A. hcl | |
| Explanation: the preffered regenerant in case of cation exchanger is hcl. | |
| 134. |
What is the preferred regenerant in case of anion exchanger? |
| A. | nacl |
| B. | naoh |
| C. | na2so4 |
| D. | na2co3 |
| Answer» B. naoh | |
| Explanation: the preffered regenerant in case of anion exchanger is naoh. regeneration is a process necessary to regenerate the resin. in this way the resin can be reused for the next demineralization process. | |
| 135. |
For obtaining Silica<5 ppm which of these should be utilized? |
| A. | sba followed by mixed be |
| B. | sba |
| C. | wba sba followed by mixed bed |
| D. | mixed bed |
| Answer» A. sba followed by mixed be | |
| Explanation: a mixed bed is usually followed after a sba to obtain silica level < 5 ppm. mixed bed constitutes both an anion and | |
| 136. |
In which year was the Ferrosand process patented? |
| A. | 1960 |
| B. | 1965 |
| C. | 1970 |
| D. | 1975 |
| Answer» B. 1965 | |
| Explanation: the manganese greensand process has been used in the united states since the 1950s. during the early years of its use, hungerford & terry, inc. of clayton, new jersey, worked to improve the process and eventually developed the ferrosand® cr process, patented in 1965. | |
| 137. |
What is the permitted concentration of manganese in drinking water? |
| A. | 30 g/l |
| B. | 40 g/l |
| C. | 50 g/l |
| D. | 60 g/l |
| Answer» C. 50 g/l | |
| Explanation: the permitted concentration of manganese in drinking water is 50g/l. the manganese greensand process has been used in the united states since the 1950s. | |
| 138. |
What is the permitted concentration of arsenic in drinking water? |
| A. | 10 g/l |
| B. | 20 g/l |
| C. | 30 g/l |
| D. | 40 g/l |
| Answer» A. 10 g/l | |
| Explanation: the permitted concentration of arsenic in drinking water is 10g/l. the permitted concentration of iron in drinking water is 200g/l. the permitted concentration of manganese in drinking water is 50g/l. | |
| 139. |
What is the minimum time of aeration? |
| A. | 20 minutes |
| B. | 40 minutes |
| C. | 60 minutes |
| D. | 80 minutes |
| Answer» C. 60 minutes | |
| Explanation: the water is aerated for a period of no less than 60 minutes. if water flow is 50 m3/h the aeration level is 100m3/h of air and tank volume is 50m3 of water. | |
| 140. |
What is the tank volume of aeration for water flow of 50m3/h? |
| A. | 40 m3 |
| B. | 50 m3 |
| C. | 80 m3 |
| D. | 100 m3 |
| Answer» B. 50 m3 | |
| Explanation: the water is aerated for a period of no less than 60 minutes. the tank volume of aeration for water flow of 50m3/h is 50 m3. | |
| 141. |
At what pH should the water be maintained? |
| A. | 6.5 |
| B. | 7.5 |
| C. | 8.5 |
| D. | 9 |
| Answer» B. 7.5 | |
| Explanation: the ph of the water should be increased to a value over ph 7.5. the decrease in the value of ph leads to increase in the acidity of water. | |
| 142. |
The aeration system will decrease the redox potential of the water. |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: the aeration system will increase the redox potential of the water. it is important to raise the potential to as high a value as possible. certainly, it should be over 200mv. | |
| 143. |
What is the minimum required redox potential of water? |
| A. | 100 mv |
| B. | 200 mv |
| C. | 300 mv |
| D. | 400 mv |
| Answer» B. 200 mv | |
| Explanation: the minimum required redox potential of water is 200 mv. manganese oxidation requires a high oxidation potential. | |
| 144. |
Manganese oxidation requires a high oxidation potential. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: manganese oxidation requires a high oxidation potential, in some cases if there is a high bod or organic content in the water it may be required to add additional oxidizing agents such as hypochlorite, | |
| 145. |
What is the desirable bed depth for AFM filtration? |
| A. | 1000 mm |
| B. | 1200 mm |
| C. | 1500 mm |
| D. | 1800 mm |
| Answer» B. 1200 mm | |
| Explanation: the desirable bed depth of afm filtration is 1200 mm. maximum bed depth can be within 3000 mm and the bulk density is 1.25-1. | |
| 146. |
What is the maximum allowable flow for backwash? |
| A. | 20 m/hr |
| B. | 45 m/hr |
| C. | 60 m/hr |
| D. | 80 m/hr |
| Answer» C. 60 m/hr | |
| Explanation: the maximum allowable water flow for backwash is 60 m/hr. the recommended water flow for backwash is 45 m/hr. | |
| 147. |
The fluoride concentration for prevention of dental caries is |
| A. | 1mg/l |
| B. | 2mg/l |
| C. | 3mg/l |
| D. | 4mg/l |
| Answer» A. 1mg/l | |
| Explanation: dental caries occurs in children. it can be prevented when the | |
| 148. |
In which process, the fluoride content of water is raised? |
| A. | chlorination |
| B. | fluoridation |
| C. | defluoridation |
| D. | flocculation |
| Answer» B. fluoridation | |
| Explanation: when the fluoride content is low, it will cause dental caries. so the fluoride content of water is raised and the process is called fluoridation. | |
| 149. |
Which of the following is not used as a fluoride compound? |
| A. | sodium fluoride |
| B. | sodium silico fluoride |
| C. | hydrofluosilicic acid |
| D. | sodium fluro carbonate |
| Answer» D. sodium fluro carbonate | |
| Explanation: sodium fluoride, sodium silico fluoride, hydrofluosilicic acid and sodium fluro carbonate are the fluoride compounds used for fluoridation. | |
| 150. |
Which of the following is the pure compound? |
| A. | sodium fluoride |
| B. | sodium silico fluoride |
| C. | hydrofluosilicic acid |
| D. | sodium fluro carbonate |
| Answer» A. sodium fluoride | |
| Explanation: sodium fluoride is the most purest compound having 95-98% purity due to which, they are commonly used for fluoridation. | |
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