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Answer the following questions: For $M^{2+}/M and M^{3+}/M^{2+}$ systems, $E^\circ$ values for some metals are as follows:

$Cr^{2+}/Cr = - 0.9 V$	$Cr^{3+}/Cr^{2+} = - 0.4 V$
$Mn^{2+}/Mn = 0 1.2 V$	$Mn^{3+}/Mn^{2+} = +1.5 V$
$Fe^{2+}/Fe = - 0.4 V$	$Fe^{3+}/Fe^{2+} = +0.8 V$

Use this data to comment upon:

1. The stability of $Fe^{3+}$ in acid solution as compared to that of $Cr^{3+}$ and $Mn^{3+}.$
2. The ease with which iron can be oxidised as compared to the similar process for either $Cr$ or $Mn$ metals.