A Best Way To Crack Gorenment Job Exams

Civil Engineering Objective Questions { Hydrology }



351.  The process of aeration of treated water helps
A. in killing bacteria
B. to remove 112S gas
C. to remove iron and manganese
D. all the above.
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352.  Consider the following statements regarding the sedimentation tanks.1. The detention time ranges between 4 to 8 hours for plain sedimentation2. The width of the tankis normally kept 10m to 12m.3. The horizontal flow velocity in sedimentation tank is generally kept 0.3 mJminute.4. The total flow from the tank in 24 hours is kept equal to maximum daily demand. Of these statements:
A. 1 and 2 are correct
B. 3 and 4 are correct
C. 1 and 4 are correct
D. 1, 2, 3 and 4 are correct
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353. Consider the following statements:1. The average theoretical time required forthe water to flow through the settling tank is called detention period.2. The amount of raw water which passes through the settling tank without being detained forthe intended time is said to be short circuited.3. The flowing through period is always more than the detention period.4. Displacement efficiency is the ratio of detention time and flow through time. Of these statements:
A. 1 alone is correct
B. 1 and 2 are correct
C. 3 and 4 are correct
D. 2 and 4 are correct
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354. Consider the following statements: Assertion A: The deposited sludge is removed from the bottom of settling tank Reason R: Due to decomposition of organic matter certain foul gases are evolved. Of these statements:
A. Both A and R are true and R is the correct explanation ofA
B. Both A and R are true and R is not the correct explanation of A
C. A is true but R is false
D. A is false but R is true
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355.  Consider the following statements regarding sedimentation aided with coagualation.1. When certain chemical compounds called coagulants are added to thewater containing very fine suspended mud particles, a gelatenous precipitate called 'floc' is formed. 2. The very fine mud particles and colloidal matter get attracted to the flocs and form the bigger sized floculated particles. 3. The coagulation is done in sedimentation tank where floculated particles settle down. 4. Coagulants are used if water turbidity is more than 30 mg per litre. Of these statements:
A. 1 and 2 are correct
B. 1 and 3 are correct
C. 1, 2, 3 and 4 are correct
D. 2, 3 and 4 are correct
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356.  Consider the following statemetns regarding coagulant (iron salt), 1. They remove much more suspended matter than the alum 2. They remove hydrogen sulphide and also its taste and odour 3. They have a limited range of pH values 4. They do not impart corrosiveness to water. Of these statements
A. 1 alone is correct
B. 2 alone is correct
C. 1 and 2 the correct
D. 3 and 4 are correct
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357.  Consider the following statements regarding the working of coagulation sedimentation plant. 1. Mixing the chemical coagulant. 2. Agitating the mixture of chemical coagulant and raw water3. Consolidation of flocin fioculation tank4. Allowing the flocculated water to enter into sedimentation tank. The correct sequence of operation is
A. 4, 2, 3, 1
B. 1, 2, 4, 3
C. 1, 2, 3, 4
D. 3, 2, 4,
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