B, on insulated stands, are each given a charge of +2.0 * 10^-6 coulomb. The distance between the spheres is 2.0 *10^-1 meter. Calculate the magnitude of the electrostatic force that the charge on sphere A exerts on the charge on sphere B

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 =