$d$-block elements form

Identify the ferromagnetic element from the following.

Which element from the following in $+3$ oxidation state forms colourless compounds?

The spin-only magnetic moment value of the ion among $Ti^{2+}$,$V^{2+}$,$Co^{3+}$,and $Cr^{2+}$ that acts as a strong oxidizing agent in aqueous solution is .......... $BM$ (nearest integer).
(Given atomic numbers: $Ti = 22, V = 23, Cr = 24, Co = 27$)

For the first row transition metals,the $E^{\Theta }$ values are:

$E^{\Theta }$	$V$	$Cr$	$Mn$	$Fe$	$Co$	$Ni$	$Cu$
$(M^{2+}/M)$	$-1.18$	$-0.91$	$-1.18$	$-0.44$	$-0.28$	$-0.25$	$+0.35$

Explain the irregularity in the above values.

Which element from the following exhibits various different oxidation states from $+2$ to $+7$?