Which of the following is a vector quantity ? a. the volume of a liquid b. the weight of a physics book c. the displacement of walking around a running track d. both b and c

D: both weight and displacement are vector quantities

vector quantities have both magnitude and direction while scalar quantities only have magnitudes

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 =