Solution Buddy

Answer the following questions in brief:

(1) What is water quality?

Ans.
Water quality describes the condition of water, including chemical, physical and biological characteristics , usually with respect to its suitability for a particular purpose such as drinking.


(2) How does water get polluted ?

Ans.
Water pollution can be caused in a number of ways such as by city sewage, Industrial waste, aquatic weeds , decomposition of dead plant and animals present in water, soil erosion, disposal of ashes, human waste, garbage thrown by people in water, mud ,etc .


(3) Write any four criteria for drinking water quality.

Ans.

i) The water should be good in taste.

ii) It should not be brackish , salty or oily.

iii) The water should be crystal clear, colourless.

iv) There should be no harmful chemicals mixed in the water.


(4) what is pH of water ?

Ans.

i) pH of water is measured on the basis of the amount of acidic or alkaline substances mixed in the water.

ii) Universal indicator is used for measurement of pH.

iii) The numbers 0 to 14 on the given scale are indicated by different coloured marks .


(5) How does oxygen get dissolved in water ?

Ans.

i) Due to the movement of air , oxygen enters from the surface of water and exits in a dissolved state.

ii) oxygen from during the photosynthesis process of aquatic plants , in wetlands or in mud is also soluble in water.

iii) The amount of dissolved oxygen depends on temperature, air pressure, and salinity of water , etc.


(6) Explain the concept of Biological Oxygen Demand (B.O.D) .

Ans.

i) Biological Oxygen Demand (B.O.D) is the amount of oxygen needed by biological organism such as bacteria in a given water sample for a breakdown of organic matter by oxidation process.

ii) The bacteria that maintain the quality of the water needs the required amount of oxygen dissolved in water for their survival.


(7) Explain the concept of Chemical Oxygen Demand (C.O.D).

Ans.

i) The Chemical Oxygen Demand (C.O.D) is a measurement of the oxygen required to oxidize soluble and particulate organic matter in water.

ii) The chemical oxygen demand of water is examined from the point of view of checking the efficiency of the sewage treatment plant.


(8) Briefly describe the consequences of exceeding the quality limit.

Ans.

i) Turbidity : People will not use muddy water for drinking as it does not look attractive / clean.

ii) pH : if the concentration is less than 7 or more than 8.5 then by chemical activities in the body are not carried out properly.

iii) Bacteria and viruses : disease like typhoid , dysentery , diarrhoea , Cholera , jaundice , polio , scribes are caused by pathogenic bacteria and viruses in the water.


(9) Write in brief about experiment of new water in Singapore .

Ans.

i) Due to shortage of water , Singapore imports water from other countries . Singapore has also set up factories to desalinate sea water and making it potable.

ii) Similarly , the waste water generated in the cities is also purified to such extent that is also used for drinking.

iii) This water is called new water.