250+ TOP MCQs on Chemical Characteristics of Waste Water and Answers

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Environmental Engineering Multiple Choice Questions on “Chemical Characteristics of Waste Water”.

1. 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
Answer: c
Clarification: The temperature and dissolved oxygen are inversely proportional to each other.

2. What is the minimum quantity of dissolved oxygen that should be present in the treated sewage?
a) 6ppm
b) 4ppm
c) 1ppm
d) 10ppm
Answer: b
Clarification: At least, 4ppm of dissolved oxygen should be present in treating sewage otherwise, fishes will die due to lack of dissolved oxygen.

3. 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
Answer: d
Clarification: 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. The presence of free ammonia in sewage represents ____________
a) Air pollution
b) Old pollution
c) Recent pollution
d) Water pollution
Answer: c
Clarification: The presence of free ammonia in sewage represents recent pollution. Which can be removed from wastewater by the nitrification process.

5. 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
Answer: c
Clarification: Potassium chromate is used for the titration of waste water with silver nitrate solution for finding the chloride content.

6. The type of solids which floats in sewage is __________
a) Suspended solids
b) Settleable solids
c) Dissolved solids
d) Total solids
Answer: a
Clarification: The suspended solids float in sewage. 1000kg of sewage contain 0.112 kg of suspended solids.

7. The presence of which of the following indicates old pollution?
a) Nitrates
b) Nitrites
c) H2S
d) Sulfates
Answer: d
Clarification: The presence of nitrates indicates the old pollution. It also means that the nitrogen is fully oxidized in sewage.

8. ________ is used to find the D.O content of sewage.
a) Winkler method
b) Chromatography
c) Kjeldahl method
d) Olfactometer
Answer: b
Clarification: 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. The permissible dose of chloride in domestic sewage is __________
a) 120ppm
b) 10ppm
c) 1ppm
d) 250ppm
Answer: a
Clarification: 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. Imhoff cone is used to measure the _______
a) Suspended solids
b) Settleable solids
c) Dissolved solids
d) Total solids
Answer: b
Clarification: 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. 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
Answer: d
Clarification: The decomposition of sewage leads to the formation of sulfur compound like H2S which produces a pungent smell.

12. Which of the following disease is caused due to lack of nitrates?
a) Diphtheria
b) Methemoglobinemia
c) Tuberculosis
d) Meningitis
Answer: b
Clarification: 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. 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
Answer: a
Clarification: At a given temperature, the maximum quantity of dissolved oxygen in sewage in wastewater is called saturated dissolved oxygen.

14. Identify the odd one of the following.
a) Fatty acids
b) Chlorides
c) Cellulose
d) Fats
Answer: b
Clarification: Chlorides are inorganic matter, whereas Fatty acids, Cellulose and Fats are organic matter.

15. The fresh sewage is acidic in nature.
a) True
b) False
Answer: b
Clarification: The fresh sewage is alkaline, but after sometime, the production of acid takes place and the pH of sewage decreases.