Explain the flow of electrons in p-type semiconductors and why it looks like a flow of positive charges.

In p type of semiconductors we know that impurity of trivalent valency is added into the pure semiconductors. Due to this trivalent impurity the bond is made between the atoms in such a way that it will show a vacant space in its bonding around an atom.

Due to the bonding of the trivalent valency of atom with the pure semiconductor atom it form a bond in which 3 electrons will share completely while in fourth valency it shows a vacancy.

This vacant space is known as holes. which will be filled by shared electrons as it is a lower energy state in the space.

Now when we see the charge sharing in this then here the vacant space is filled due to the shifting of valance electrons in the bonds. As electron will fill the position of hole then it will create the vacancy at the previous position of the electron and this continues till the vacancy is filled by different electron.

As we can see that holes are created at different positions due to flow of electrons then we can relate is to the flow of positive charge as its motion is opposite the flow of electrons.

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 =