Waste Water Engineering Multiple Choice Questions on “Total Dissolved Solids – 1”.
1. Cations with ______ increase corrosivity.
a) Bromide
b) Chloride
c) Iodide
d) Sulphide
Answer: b
Clarification: Cations combined with carbonates can lead to an increase in the scale formation and bitter taste. Cations combined with chloride can lead to an increase in the corrosivity.
2. _______ is the universal solvent.
a) Organic solvents
b) Inorganic solvents
c) Water
d) Acid
Answer: c
Clarification: Water is a good solvent and picks up impurities easily. Pure water is tasteless, colourless and odourless and is often called the universal solvent.
3. Total dissolved solids consist of cations only.
a) True
b) False
Answer: b
Clarification: The total dissolved solids concentration is the sum of the cations (positively charged) and anions (negatively charged) ions in the water.
4. _______ is used as an indicator test to determine the general quality of the water.
a) Oxidation test
b) Reduction test
c) Total dissolved solids test
d) Organic test
Answer: c
Clarification: The total dissolved solids test is used as an indicator test to determine the general quality of the water. The sources of total dissolved solids can include all of the dissolved cations and anions.
5. TDS decreases the efficiency of hot water heaters.
a) True
b) False
Answer: a
Clarification: The concentration of the dissolved ions may cause the water to be corrosive, salty or brackish taste, result in scale formation and interfere and decrease the efficiency of hot water heaters.
6. At what temperature is the filtrate dried in a TDS laboratory test?
a) 100˚C
b) 102˚C
c) 103˚C
d) 105˚C
Answer: c
Clarification: In a laboratory setting, the total dissolved solids are determined by filtering a measured volume of sample through a standard glass fiber filter. The filtrate (i.e., filtered liquid) is then added to a preweighed ceramic dish that is placed in a drying oven at a temperature of 103˚C.
7. What is the temperature required to remove occluded water?
a) 170˚C
b) 180˚C
c) 190˚C
d) 200˚C
Answer: b
Clarification: After the sample dries, the temperature is increased to 180˚C to remove occluded water i.e., water molecules trapped in the mineral matrix.
8. What is the standard for TDS for aesthetic considerations?
a) 250 mg/l
b) 500 mg/l
c) 750 mg/l
d) 1000 mg/l
Answer: b
Clarification: High total dissolved solids may affect the aesthetic quality of the water; interfere with washing clothes and corrode plumbing fixtures. For aesthetic reasons, a limit of 500 mg/l (milligrams per litre) has been established as part of the Secondary Drinking Water Standards.
9. On which of the factors does the relationship between TDS and conductivity does not depend on?
a) Type of ions
b) Nature of ions
c) Nature of suspended solids
d) Type of microbes
Answer: d
Clarification: There are various factors on which the relationship between TDS and conductivity depends on and they are a type of ions, their nature and also the nature of suspended solids.
10. The primary dissolved solids are assumed to be _________
a) KI
b) KCl
c) MnCl
d) AlCl
Answer: b
Clarification: Total Dissolved Solids can be measured in the field using an electronic pen and it then calculates the total dissolved solids assuming that the primary dissolved minerals are either a combination of NaCl or KCl.
11. What is the secondary standard for TDS?
a) 400 mg/l
b) 500 mg/l
c) 600 mg/l
d) 700 mg/l
Answer: b
Clarification: Primary Standards are based on health considerations and Secondary Standards are based on taste, odour, colour, corrosivity, foaming and staining properties of water.
12. The treatment options for an elevated total dissolved solid depends on _______
a) Quantity of water
b) Nature of ions
c) Nature of suspended solids
d) Type of microbes
Answer: b
Clarification: The treatment options for elevated total dissolved solids really depend on the nature of the cations and anions. It is possible to remove these solids using a water softener.