What is the ratio of Fe+3 ions to O2 - ions in a neutral compound?

a. 1:2

b. 2:1

c. 2:3

d. 3:2

In a neutral compound, the charges must balance, the net charge should be zero.

Since the charge of Fe is 3 + and that of O is 2-, therefore, there should be 2 Fe 3 + ions per 3 O2 - ions in order to have a net charge of zero.