Asubstance has a volume of 10.0 cm3 and a mass of 89 grams. what is its density?
0.11 g/cm3
8.9 g/cm3
99 g/cm3
79 g/cm3

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.

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 =