MolSynapsequestion bank
MolSynapse / Question bank / Environmental Chemistry / Water pollution, BOD and COD
JEE Main levelSingle correct optionDifficulty 2 of 3ev123

After a bloom of algae in a pond, the dissolved oxygen of the water falls sharply because:

  1. Asunlight cannot reach the surface of the pond
  2. Bphosphate directly reacts with dissolved oxygen
  3. Caerobic bacteria use up oxygen while decomposing the dead algae
  4. Dalgae release large amounts of hydrogen

Answer: C

Dead algae are decomposed by aerobic bacteria, which consume dissolved oxygen. The increased BOD leads to oxygen depletion and fish kills.
Practice Environmental Chemistry More on Water pollution, BOD and COD
Previous questionNext question

More questions on Water pollution, BOD and COD