Two charged particles with opposite signs but the same magnitude of charge enter a magnetic field that is perpendicular to their direction of motion. How will the motion of the two particles differ when they enter the
magnetic field?

neither accurate nor precise.

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 =