Test: Sedimentation With Coagulation


10 Questions MCQ Test Environmental Engineering | Test: Sedimentation With Coagulation


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Attempt Test: Sedimentation With Coagulation | 10 questions in 25 minutes | Mock test for Chemical Engineering preparation | Free important questions MCQ to study Environmental Engineering for Chemical Engineering Exam | Download free PDF with solutions
QUESTION: 1

What is formed when coagulant is added to water?

Solution:

Explanation: When coagulant is added to water, then white gelatinous precipitate is formed called as floc.

QUESTION: 2

 The chemical composition of Alum is 

Solution:

Explanation: Alum is the most common and universal coagulant used in water treatment having chemical composition Al2 (SO43.18H2O.

QUESTION: 3

The chemical compound which is insoluble in water, formed when alum is added to water is _____ 

Solution:

Explanation: Al2 (SO4)3.18H2O + 3Ca (HCO3)2 = 2Al (OH)3 + 3CaSO4 + 18H2O + CO2
Where Al (OH)3 is insoluble in water.

QUESTION: 4

 Which gas is released when alum is added to water? 

Solution:

Explanation: Carbon dioxide gas is released when alum is added to water, which is corrosive to metals.

QUESTION: 5

 What indicates the permanent hardness when alum is added to water? 

Solution:

Explanation: The presence of calcium sulfate indicates the permanent hardness in water when alum is added to water.

QUESTION: 6

 Alum is effective when pH of water is between ____

Solution:

Explanation: Alum is effective when pH of water is between 6.5-8.5. Its dose depends on turbidity, color, taste, pH and temperature of water.

QUESTION: 7

 Why Alum is preferred over other coagulants?

Solution:

Explanation: Alum is preferred over other coagulants because it reduces the taste and odor in addition to turbidity and produce lighter flocs that can be broken easily.

QUESTION: 8

The chemical composition of Chlorinated Copperas is 

Solution:

Explanation: 6FeSO4.7H2O2 +3Cl2 = 2Fe2(SO4) 3 + 2FeCl3 +7H2O
The ferric sulfate and ferric chloride so formed are called as Chlorinated Copperas.

QUESTION: 9

Ferric chloride is effective over a pH range of

Solution:

Explanation: Ferric chloride is effective over a pH range of 3.5-6.5 and above 8.5 whereas if Ferric sulfate is used then, it is effective over a pH range of 4-7 and above 9.

QUESTION: 10

Why Magnesium carbonate is not commonly preferred as coagulant?

Solution:

Explanation: When magnesium carbonate and lime are dissolved in water, magnesium hydroxide and calcium carbonate are formed which are soluble in water and sludge is formed in slurry form, so they are not commonly used.

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