What is the density of an unknown metal that has a mass of 158 g and a volume of 20 ml

7.9g/ml

Explanation:

Density is defined as the ratio of mass of a body to its unit volume.

Density = Mass/volume.

Given mass = 158g

Volume = 20ml

Density = 158/20

= 7.9g/ml

The density of the unknown metal is 7.9g/ml

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 =