<span>The answer is 2:3. Because the lowest common denominator of 2 and 3 is 6, we find that for every 2 Fe3+ ions, we would need 3 O2- ions to neutralize the charge. The other answers do not fit this idea, as the math doesn't then add up to come to a neutral charge.</span>
Go here and see how:
http://www.rsc.org/learn-chemistry/resource/res00000698/using-indigestion-tablets-to-neutralise-an-acid?cmpid=CMP00005978
Answer:
1) mass and type of material
2) type of material
3) temperature
Explanation: