How do the number of electrons in an energy level affect bond formation?

Concept:

When an atom has incomplete number of electron in its outermost orbit then it has great tendency to react with another atom which satisfies their octate either by sharing or by transferring their electrons. The involved electrons are called valence electrons. These electrons will effect the energy level because of the transition of these electrons from one energy level to another energy level.  

In case of electrovalent compound, the valance electron complete their octate by transferring their valence electrons while in the covalent compound, they complete their octate by the sharing of their valence electrons.

Hence, the valence electron of the atom effect the energy levels by the transition from one state to another state in the bond formation.

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%

i think its 100.

hope this !