Which of these elements has an atom with the most stable outer electron configuration? 1.Br 2.Ne 3.Zn 4.Ag

Ne

Explanation:

Neon is the element with the most stable outer electron configuration because it has eight valence electrons that fill the outer shell. Eight electrons in the outer shell is the most stable arrangement of electrons. Neon is also a noble gas which means that due to it already having a complete outer shell, it doesn't lose, gain, or share electrons. Therefore, it is stable.

Hope that helps.

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%