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Biology

The graph given below represents the effect of sewage discharge on some important characteristics of river.

Select the correct option with respect to the peaks A and B.

BiologyGeneral

  1. Peak A – Sharp increase in BOD, disappearance of clean water organisms,    
  2. Peak A – Increase in dissolved oxygen, reappearance of clean water organisms,    
  3. Peak A – Sharp increase in BOD, appearance of clean water organisms,    
  4. Peak A – Increased number of anaerobic bacteria, disappearance of clean water organisms,    

    Answer:The correct answer is: Peak A – Sharp increase in BOD, disappearance of clean water organisms,– Increase in dissolved oxygen, reappearance of clean water organisms.
    Peak B – Sharp decline in dissolved oxygen, disappearance of clean water organisms.
    Peak B – Increase in dissolved oxygen, disappearance of clean water organisms.
    Peak B – Sharp decline is dissolved O2, reappearance of clean water organisms.

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