1.Which of the following elements has the largest known oxidation number (in magnitude)?
Pt
Au
Os
Fe
Ru
2.Which of the following metals has the highest melting point?
Al
Mg
K
Na
Ca
I know that Ca is wrong because I tried it, so I really think it has to be Na that has the highest melting point out of all the others.
You can go to www.webelements.com an check on the melting point of each as well as the oxidations states of each.