The answer is (3) Cu2O. Copper (I) has an oxidation state of +1 (that's what the "I" indicates). You can also think of this as copper (I) having a charge of +1. Oxygen has an oxidation state of -2 (that's just a rule you have to know), and you can think of it as oxygen having a charge of -2. You need oxidation numbers in a neutral compound to add up to 0 (or charges in a neutral compond to add up to 0), so you need two Cu to balance the O, which is Cu2O.
The correct answer is 7 I just took the test :)
<span>your answer is Ca3</span>(PO4)2<span>, </span>
Answer:
Any of the six chemical elements that markup group1
of the periodic table.
Explanation: