What is the atomic number of an element having $ns^1$ electronic configuration and belonging to the $3d$ transition series?

The common positive oxidation states for an element with atomic number $24$ are:

For $M^{2+} / M$ and $M^{3+} / M^{2+}$ systems,the ${E^{\Theta}}$ values for some metals are as follows:
$Cr^{2+} / Cr : -0.9 \ V$
$Cr^{3+} / Cr^{2+} : -0.4 \ V$
$Mn^{2+} / Mn : -1.2 \ V$
$Mn^{3+} / Mn^{2+} : +1.5 \ V$
$Fe^{2+} / Fe : -0.4 \ V$
$Fe^{3+} / Fe^{2+} : +0.8 \ V$
Use this data to comment upon:
$(i)$ The stability of $Fe^{3+}$ in acid solution as compared to that of $Cr^{3+}$ or $Mn^{3+}$ and
$(ii)$ The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.

On what ground can you say that scandium $(Z=21)$ is a transition element but zinc $(Z=30)$ is not?

Maximum oxidation state is shown by

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.