How many electrons must be added to an object to give it an overall net charge of -3.0 x 10^-7 c? the charge of an electron is -1.602 x 10^-19 c.
1.9 x 10^12 electrons
3.1 x 10^13 electrons
2.0 x 10^10 electrons
1.4 x 10^14 electrons

iron would move it is magnetic there is a mag field around the current in the wire

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 =