Two bottles were half filled with water from Ganga ('P') and kaveri ('Q') and kept under identical airtight conditions for 5 days. The oxygen was determined to be 2% in bottle ('P') and 10% in bottle ('Q'). What could be the cause of this difference?
Ganga is more polluted than Kaveri
Ganga is more polluted than Kaveri. Lower DO [Dissolved Oxygen] indicates more polluted water. In this case DO of Ganga is 2% which is less than DO of Kaveri which is 10%.