14. Iron (III) is best determined by addition of excess EDTA, followed by back-titration with a metal ion that reacts rapidly with EDTA. A 700.0-mg sample is dissolved, 20.00 mL of 0.0500 M EDTA is added, and the excess EDTA is titrated with 5.08 mL of 0.0420 M copper (II). Calculate the percentage of Fe2O3.

n has four pairs of electrons in the valence shell, electrons repel one another ,n has 7 protons in its nucleus, and since n has 7 protons, it must fill the second shell, giving it 4 pairs of electrons. the electrons form 3 bonds and 1 lone pair of electrons. each pair of electrons repels the other pairs, so they are equally far apart.

so all of the above