Which of the following statements is true about the speed at which sound waves travel? A:Sound travels faster through air

B:Sound travels faster in a vacuum

C:Sound travels faster through water

D:Sound travels faster through a solid

sound waves travel faster in solid than water or air.

In vacuum sound waves don't travel at all

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 =