Which of the following ions has the highest magnetic moment?

Which of the following electronic configurations belongs to the $d$-block elements?

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:

Compare the general characteristics of the first series of the transition metals with those of the second and third series metals in the respective vertical columns. Give special emphasis on the following points:
$(i)$ electronic configurations,
$(ii)$ oxidation states,
$(iii)$ ionisation enthalpies,and
$(iv)$ atomic sizes.

Consider the following pairs of elements and identify the pairs of elements which have nearly same atomic radius.
$I$. $Y, La$
$II$. $Zr, Hf$
$III$. $Mo, W$
$IV$. $Cr, Mo$

Properties common to the elements manganese,iron,cobalt,nickel,and copper include the ready formation by them all of:
$I$. Coloured ions in aqueous solution
$II$. Oxides of nitrogen are formed on reaction with concentrated $HNO_3$
$III$. Chlorides of formula $MCl_2$ and $MCl_3$