Question

Four samples of water ${\text{A,B,C and D}}$ have ${\text{DO}}$ values ${\text{1 mg/L, 3 mg/L, 5 mg/L and 8 mg/L}}$, respectively. Which one is more polluted water?
1. ${\text{A}}$
2. ${\text{B}}$
3. ${\text{C}}$
4. ${\text{D}}$

Answer 1

It can be defined as a measure of the oxygen concentration that is dissolved in medium relative to the maximum concentration that can be dissolved in the medium at constant conditions of temperature and pressure. oxygen saturation can be represented as the symbol ${S_{{O_2}}}$.A dissolved oxygen probe such as an oxygen sensor can be used to measure it. Percent is the standard unit of oxygen saturation.

Complete step by step answer:
One of the most important indicators of water quality is dissolved oxygen (${\text{DO}}$).
The colder the water, the more oxygen it can retain.
Less oxygen can be dissolved in the water as the water becomes warmer. Thus, the lower the ${\text{DO}}$ value, the water sample will be more polluted.
From the given, four samples of water ${\text{A,B,C and D}}$ have ${\text{DO}}$ values ${\text{1 mg/L, 3 mg/L, 5 mg/L and 8 mg/L}}$, respectively.
“A” samples have low ${\text{DO}}$ value. Hence, it is more polluted.
Therefore, the correct option is (1).

Additional information:
-It is important for fish and other aquatic organisms to survive.
-Due to the aeration action of winds, oxygen dissolves in surface water.
-As a by-product of aquatic plant photosynthesis, oxygen is also introduced into the water. Marine animals are not able to survive when dissolved oxygen becomes too less.

Note: The levels of concentration of dissolved oxygen can be expressed as milligrams per litre ( ${\text{mg/L}}$) or parts per million ( ${\text{ppm}}$) The high accuracy of the DO measurement depends entirely on proper calibration and maintenance. The polarographic DO sensor employs the most practical and consistently accurate method for field measurements.