Which transition series includes elements $Co$ and $Mo$ respectively?

Which of the following pairs of substances exhibit paramagnetism among $K_2SO_4$,$MgCl_2$,$FeSO_4$,$NiCl_2$,and $ZnO$?

Which of the following elements has the maximum density?

The correct statement about iron includes:
$I$) The highest oxidation state of iron is $+ 6$ in $K_2FeO_4$.
$II$) The iron shows $+ 2$ oxidation state with six electrons in the $3d$ orbitals.
$III$) The common oxidation state of iron is $+ 3$ with five unpaired electrons in the $3d$ orbital.

Among the following,the incorrect statement about transition metals is:

The correct order of spin-only magnetic moment (in $BM$) for $Mn^{2+}$,$Cr^{2+}$,and $Ti^{2+}$ ions is: