Periodic Table of the Elements review questions...?

Question

I'm working on my chem homework, and there are two questions that I can't find about in my notes:

27. Which metal is most likely obtained by the electrolysis of its fused salt?

a. Au
b. Ag
c. Li
d. Zn

29. Which of the following elements can form more than one binary compound with Oxygen?

a. sodium
b. magnesium
c. iron
d. calcium

If you could please explain the answers too so I can understand it I would be very grateful. Thank you in advance!

Answer 1

27: Li, because it's so reactive, you can't obtain it by electrolysis of the aqueous solution.

29: FeO and Fe2O3