NEET Questions Solved

BOARD

Explain the effect on the characteristics of a river when   (3 marks)

urban sewage is discharged into it.

- Rise in organic matter , leads to increased microbial

 activity / growth of microbes= ½ + ½

-It results in decrease in dissolved oxygen / rise in BOD /

rise in Biochemical Oxygen Demand = 1

- Leads to fish mortality / algal bloom / colour change / foul odour /

increase in toxicity (Any two) = ½ + ½                           (1+1+1 marks)

Difficulty Level:

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