If an element has 3 valence electrons, what charge will likely form on its ion

Apeak with a retention time of 407 s has a width at half-height (w1/2) of 7.6 s. a neighboring peak is eluted 17 s later with a w1/2 of 9.4 s. a compound that is known not to be retained was eluted in 2.5 s. the peaks are not baseline resolved. how many theoretical plates would be needed to achieve a resolution of 1.5?

How many moles of al3+ ions are in 1.25 moles of al2o3

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.