(a) 6.5 – 7.5
(b) 2.0 – 3.5
(c) 3.5 – 5.0
(d) 9.0 – 10.5
Correct option – ( a )
Explanation – for the life of the freshwater plants and animals the pH of water should neither be acidic nor basic , that is it should be basic . So the range will be 6.5 – 7.5