Question 10 of 10 At what point is the half-life of a radioactive isotope reached?
O A. When all the parent nuclei in a sample have become daughter
nuclei
OB. When half the daughter nuclei in a sample have become parent
nuclei
O C. When all the daughter nuclei in a sample have become parent
nuclei
O D. When half the parent nuclei in a sample have become daughter
nuclei
SUBMIT

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%