Essie is working with a 100% stock concentration of Clorox. She decides to add 150 µL of bacteria to a tube containing 2 mL of nutrient broth and then adds 200µL of the Clorox stock to the tube as well. What is the unknown concentration of the tube?

8.5%

Explanation:

The unknown final concentration can be found out by the dilution formula C1V1 = C2V2

where,

C1 = Starting concentration = 100%

V1 = Starting volume = 200μL

C2 = Final concentration

V2 = Final volume = 2350μL ( 2000 + 150 + 200 )

So,

100 * 200 = C2 * 2350

C2 = (100 * 200) / 2350

= 20000 / 2350

= 8.5%

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.