Which metal exhibits more than one oxidation state?

The components of German silver alloy are:

Select the $CORRECT$ set of group number and period of element $Uub$ (Ununbium,now known as Copernicium,$Cn$).

Which one of the following ions exhibits the highest magnetic moment?

Given below are two statements :
Statement $I$ : The higher oxidation states are more stable down the group among transition elements unlike $p-$block elements.
Statement $II$ : Copper can not liberate hydrogen from weak acids.
In the light of the above statements,choose the correct answer from the options given below :

The electronic structure $(n - 1)d^{1 - 10}ns^{0 - 2}$ is characteristic of