[Rachael]

Now if your lab partner determined that there were 1.341 x 1019 atoms of O in an unknown sample of Mg(NO3)2, how many milligrams would the unknown sample weigh?

I know that you have to convert something to moles..but I don't know what and yeah I'm basically confused...

[Albert]

Using the value of Avogadro's number I found in the miscellaneous box of this very website:

1 mol : 6.0221367 X 10²³= x mol : 1.341 x 10¹⁹

[Rachael]

gracias