Acontainer full of mercury weighs 1000g. the empty container weighs 320 g. the density of the mercury is 13.6 g? cm3. what is the volume of the box ?

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 =

snell's law

refractve index = sin incidence / sin refraction