Need to draw structural formula for these names

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

In a ni-cd battery, a fully charged cell is composed of nickelic hydroxide. nickel is an element that has multiple oxidation states. assume the following proportions of the states: nickel charge proportions found 0 0.17 +2 0.3 +3 0.33 +4 0.5 (a) determine the mean of the nickel charge. enter the answer to 2 decimal places.(b) determine the cumulative distribution function of nickel charge.

How many grams of iron can be made from 16.5 grams of fe2o3