The term “water cycle” is used to describe the movement of water on the earth and in the earth’s atmosphere. Do you think that your diagram on Student Sheet 39.1, “Talking Drawing: Contaminants and the Water Cycle,” is a good summary of the water cycle? Why or why not?

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =

answerdmitry mendeleyev made a workable classification of the elements