Q. A lake near a village suffered heavy mortality of fishes within a few days. Consider the following reasons for this I. Lots of urea and phosphate fertilizers were used in the crops in the vicinity. II. The area was sprayed with DDT by an aircraft. III. The lake water turned green and stinky. IV. Phytoplankton populations in the lake declined initially thereby greatly reducing photosynthesis. Which two of the above were the main causes of fish mortality in the lake?
A) II and III
B) III and IV
C) I and III
D) I and II
Explanation
A lake near a village suffered heavy mortality of fishes within a few days, because lots of urea and phosphate fertilizers were used in the crops in the vicinity and the area was sprayed with DDT by an aircraft.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.