According to Dalton, if 2 grams of element X combine with 4 grams of element Y to form compound XY, how many grams of element X would combine with 28 grams of element Y to form the same compound? A. 6 B. 12 C. 18 D. 24

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray

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 =