Which coefficient of O2 is needed to balance the equation C3H8 + O2 → 3CO2 + 4H2O?

5

Explanation:

Count the number of moles of O in the product side:

3x2 + 4

= 10

Divide it by 2 since O exists as diatomic molecule (O2)

10/2 = 5

Therefore, the coefficient required is 5.

the rearrangement of particles in a physical change. hope this

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 =