What part of the atom determines if it will combine or break apart from other substances?

Explanation:

The atom consist of three parts which are following

The proton and neutron form nucleus of an atom. It is present at center of an atom. They have positive charges, while electrons remained outside the nucleus in particular energy levels or shell around the nucleus.

During combination or breaking of substances ,only arrangements of electrons take place. The valence shell electrons decide whether they have to combine or not, while nucleus remained unchanged during any reactions.

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%

all eukaryotic cell have mitochondria : )