1.The range for threshold odour number is __________
a) 0-3
b) 1-5
c) 1-3
d) 0-5
Explanation: The maximum value of Threshold odour number is 3 and its range is 1-3. The threshold odour number is used to measure the intensity of taste and odour
2. Threshold odour number testing is preferred in hot water.
a) True
b) False
Explanation: TON testing is preferred in cold water as in hot water due to increase in temperature, taste and odour can change
3.One JTU is equivalent to turbidity produced by __________
a) 1mg of fine silica dissolved in 1L of distilled water
b) 1g of fine silica dissolved in 1L of distilled water
c) 1g of fine silica dissolved in 1ml of distilled water
d) 1mg of fine silica dissolved in 1ml of distilled water
Explanation: 1 JTU is equivalent to turbidity produced by 1mg of fine silica dissolved in 1L of distilled water. It is called as Jackson’s turbidity unit and is based on the absorption principle.
4. If the PO value is 6, what does it imply?
a) No perceptible odour
b) Very faint odour
c) Very distinct odour
d) Extremely strong odour
Explanation: The PO value indicates the odour intensity. 6 is the maximum PO value and it indicates extremely strong odour.
5. The range of temperature of water that is required to do the temperature test is __________
a) 10-250C
b) 0-250C
c) 10-300C
d) 20-300C
Explanation: To do the temperature test of water, its temperature should be between 100C and 250C and the temperature higher than 250C is considered objectionable.
6. Which of the following statement is wrong regarding turbidity?
a) It is an extent to which light is absorbed by particles in the water
b) It is expressed in ppm
c) It depends on the fineness of particle present in the water
d) Turbidity rod is a laboratory method to measure turbidity
Explanation: Turbidity rod is a field method not a laboratory method to measure turbidity.
7. The permissible limit of turbidity of domestic water is ____ ppm.
a) 5-10
b) 1-5
c) 10-50
d) 10-30
Explanation: According to WHO, the permissible limit for drinking water is 5NTU.
8. What is the full form of NTU in context with turbidity?
a) Number of transfer unit
b) Neurological turbidity unit
c) Nephelometric turbidity unit
d) Network terminal unit
Explanation: The value of turbidity measured by nephelometer is expressed in terms of NTU. Sometimes, it is referred as FTU or Formazin turbidity unit
9. When depth of insertion of turbidity rod increases, the reading in the turbidity rod ___
a) Decreases
b) Increases
c) First decrease, then increase
d) Remains constant
Explanation: Turbidity rod is inserted inside the water and the reading at which needle becomes invisible gives the turbidity
10. Chlorides are estimated by titration with a standard silver nitrate solution by using _______ as an indicator.
a) Potassium manganate
b) Potassium chloride
c) Potassium chromate
d) Potassium dichromate
Explanation: 2-3 drops of potassium chromate are added to appropriate amount of water sample and then it is titrated with a standard solution of silver nitrate