10. In an elastic collision, an object with momentum 25 kg. m/s collides with another object moving to the right that has a
momentum 35 kg . m/s. After the collision, both objects are still moving to the right, but the first object's momentum
changes to 10 kg. m/s. What is the final momentum of the second object?
a. 10kg. m/s
b. 20 kg · m/s
c. 35 kg · m/s
d. 50 kg · m/s

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 =