Given below are two statements :

Statement $I$ : If $BOD$ is $4\,ppm$ and dissolved oxygen is $8\,ppm$, then it is a good quality water.

Statement $II$ : If the concentration of zinc and nitrate salts are $5 ppm$ each, then it can be a good quality water.

In the light of the above statements, choose the most appropriate answer from the options given below :

Summarize the quantities and differentiated quantities of different metals and ions at the international level of drinking water. 

Give the examples of particulates pollutants.

Give the details of different layer of atmosphere and briefly describe about the substance in it.

What is Eutrophication ?