A ball of 5 KG is moving towards the wall at 6 M/S. After a while, it hits the wall and rebounds back at 4 M/S in the opposite direction. What is the work done on it?

vapour or gas assuming atmospheriv pressure

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 =