What happens to light when it strikes a concave or convex lens?.

a. are

because growing process had stoped after 4-5 year

float.

archimedes' principle

denser than water sinks in water.

denser than mercury would sink in it

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 =