Kaplan Gchem Q

[dental13]

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Iron reacts with element X to form the compounds FeX
and Fe3X2. When copper reacts with element X, the
expected compound(s) should be
A. CuX and Cu3X2.
B. Cu2X and Cu6X.
C. Cu3X only.
D. CuX2 only.
E. Cu3X and Cu3X2.

The Answer: E
I was able to find out Fe would form +3 and +2 cations from the question, but how are we suppose to know Cu would from either +1 or +2? are we suppose to memorize oxidation numbers of transition metals?
or is there a way to find out from periodic table?

 

[JonLee]

Well to answer this question right you do need to know the oxidation numbers of copper and iron.
There really is no way to figure out ox. numbers by looking at the periodic table. Just got to memorize them.
If I were you I'd just memorize the ox. #s of the more common one's you will probably see like: Au,Ag, Hg, Cu,Fe, Cr, Zn...