What metals are in German silver alloy?

$A$ transition metal $M$ among $Sc, Ti, V, Cr, Mn$ and $Fe$ has the highest second ionisation enthalpy. The spin only magnetic moment value of $M^{+}$ ion is $. . . . . . . BM$ (Near integer)
(Given atomic number $Sc: 21, Ti: 22, V: 23, Cr: 24, Mn: 25, Fe: 26$)

Match the following aspects with the respective metal.

Aspects	Metal
$a$. The metal which reveals a maximum number of oxidation states	$i$. Scandium
$b$. The metal although placed in $3d$ block is considered not as a transition element	$ii$. Copper
$c$. The metal which does not exhibit variable oxidation states	$iii$. Manganese
$d$. The metal which in $+1$ oxidation state in aqueous solution undergoes disproportionation	$iv$. Zinc

Select the correct option.

Which of the following has the maximum number of unpaired electrons?
(Atomic numbers: $Fe=26, Co=27, Mn=25, Cr=24$)

The magnetic moment of $Gd^{3+}$ is ....... $B.M.$ $(Z = 64)$

Effective magnetic moment of $Sc^{3+}$ ion is