Which of the following alloys is used to construct marine condenser tubes of ships?

The number of unpaired electrons in $Mn^{2+}$ ion is

Which of the following has the maximum number of unpaired electrons?

Ferrous ion changes to $X$ ion upon reacting with acidified hydrogen peroxide. The number of $d$-electrons present in $X$ and its magnetic moment (in $BM$) are,respectively:

The maximum number of unpaired electrons is present in

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 :