Question

In a polluted lake,

• A. BOD and DO are high
• B. BOD is high and DO is low
• C. Both are low
• D. BOD is low and DO is high

Answer 1

The correct option is B BOD is high and DO is low

Biochemical oxygen demand or biological oxygen demand is a measurement of the amount of dissolved oxygen (DO) that is used by aerobic microorganisms while decomposing organic matter in water. A high BOD indicates two things:
1. High level of microorganisms in the water, and
2. High content of organic material in the water that is broken down by the organisms. This is an indication of organic pollution.

Hence, in a polluted lake, BOD will be high and DO will be low.