Please i have an exam monday and i dont know how to answer it help. ( A 250.0-mL aqueous solution contains 45.1 mg of a pesticide Express the pesticide's concentration in weight percent, parts per million, and parts per billion.)

a

explanation:

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.

it should be all of them because it asks if you included all of those in your answer

explanation: