Question

The ions Cr3+ and O2- combine to form the ionic compound chromium oxide. In what proportions do these ions combine to produce a neutral compound?

Answer 1

Your answer for plato is 2:3

Answer 2

For the compound formed to be neutral, the charge should be zero. This means that the positive charge should be equal to the negative charge. The balanced chemical reaction forming the neutral chromium oxide is shown below.
2Cr3+ + 3O2- ---> Cr2O3