8. The regulatory limit of Pb in drinking water according to US EPA is 15.00 ppb. What is the molality of Pb?

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

the answer to your question is c

answer; the numbers of valence electrons in the acetic acid molecule (ch3co2h) is 24;

c. 4.54 x 10–12 j happens to be correct