Engineering Questions with Answers - Multiple Choice Questions

Environmental Engineering MCQ – Chemical Characteristics of Waste Water

1 - Question

The temperature of sewage increases. What will be the effect on the dissolved oxygen in sewage?
a) Remains constant
b) Increase
c) Decrease
d) No effect

View Answer

Answer: c
Explanation: The temperature and dissolved oxygen are inversely proportional to each other.




2 - Question

What is the minimum quantity of dissolved oxygen that should be present in the treated sewage?
a) 6ppm
b) 4ppm
c) 1ppm
d) 10ppm

View Answer

Answer: b
Explanation: At least, 4ppm of dissolved oxygen should be present in treating sewage otherwise, fishes will die due to lack of dissolved oxygen.




3 - Question

The presence of which of the following in sewage indicates nitrogen content before decomposition of sewage?
a) Nitrites
b) Nitrates
c) Free ammonia
d) Albuminoid nitrogen

View Answer

Answer: d
Explanation: The presence of Albuminoid nitrogen in water indicates the decomposition of sewage has not taken place.It nitrogen is also called as organic nitrogen.




4 - Question

The presence of free ammonia in sewage represents ____________
a) Air pollution
b) Old pollution
c) Recent pollution
d) Water pollution

View Answer

Answer: c
Explanation: The presence of free ammonia in sewage represents recent pollution. Which can be removed from wastewater by the nitrification process.




5 - Question

Which chemical is used for the titration of waste water for finding its chloride content?
a) Potassium chloride
b) Sodium chloride
c) Potassium chromate
d) Potassium dichromate

View Answer

Answer: c
Explanation: Potassium chromate is used for the titration of waste water with silver nitrate solution for finding the chloride content.




6 - Question

The type of solids which floats in sewage is __________
a) Suspended solids
b) Settleable solids
c) Dissolved solids
d) Total solids

View Answer

Answer: a
Explanation: The suspended solids float in sewage. 1000kg of sewage contain 0.112 kg of suspended solids.




7 - Question

 The presence of which of the following indicates old pollution?
a) Nitrates
b) Nitrites
c) H2S
d) Sulfates

View Answer

Answer: d
Explanation: The presence of nitrates indicates the old pollution. It also means that the nitrogen is fully oxidized in sewage.




8 - Question

________ is used to find the D.O content of sewage.
a) Winkler method
b) Chromatography
c) Kjeldahl method
d) Olfactometer

View Answer

Answer: b
Explanation: Wrinkler method is used to find the D.O content of sewage where the D.O content is proportional to the titration of iodine with S2O32- solution.




9 - Question

The permissible dose of chloride in domestic sewage is __________
a) 120ppm
b) 10ppm
c) 1ppm
d) 250ppm

View Answer

Answer: a
Explanation: Domestic sewage includes waste from kitchen, laundry, toilet, bathroom, etc., which contain higher amount of chloride content, so the permissible dose of 120ppm is kept for domestic sewage.




10 - Question

Imhoff cone is used to measure the _______
a) Suspended solids
b) Settleable solids
c) Dissolved solids
d) Total solids

View Answer

Answer: b
Explanation: Imhoff cone is used to measure the settleable solids where wastewater is allowed to stand for a specific time, solids get settled down and the readings are taken through the graduations on the cone.




11 - Question

 The decomposition of sewage takes place, causing a pungent smell. Which of the following causes the pungent smell?
a) CO2
b) H2SO4
c) HCL
d) H2S

View Answer

Answer: d
Explanation: The decomposition of sewage leads to the formation of sulfur compound like H2S which produces a pungent smell.




12 - Question

Which of the following disease is caused due to lack of nitrates?
a) Diphtheria
b) Methemoglobinemia
c) Tuberculosis
d) Meningitis

View Answer

Answer: b
Explanation: Methemoglobinemia is a disease caused due to lack of nitrates in the body where the concentration of methemoglobin in red blood cells becomes greater than 1%.




13 - Question

The maximum quantity of dissolved oxygen present in wastewater is called __________
a) Saturated dissolved oxygen
b) Maximum dissolved oxygen
c) Optimal dissolved oxygen
d) Peak dissolved oxygen

View Answer

Answer: a
Explanation: At a given temperature, the maximum quantity of dissolved oxygen in sewage in wastewater is called saturated dissolved oxygen.




14 - Question

Identify the odd one of the following.
a) Fatty acids
b) Chlorides
c) Cellulose
d) Fats

View Answer

Answer: b
Explanation: Chlorides are inorganic matter, whereas Fatty acids, Cellulose and Fats are organic matter.




15 - Question

The fresh sewage is acidic in nature.
a) True
b) False

View Answer

Answer: b
Explanation: The fresh sewage is alkaline, but after sometime, the production of acid takes place and the pH of sewage decreases.

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