(i) The $E^{⊝}$value for Fe${}^{3+}$/Fe${}^{2+}$ is higher than that for Cr${}^{3+}$/Cr${}^{2+}$ and lower than that for

Mn${}^{3+}$/Mn${}^{2+}$. So, the reduction of Fe${}^{3+}$ to Fe${}^{2+}$ is easier than the reduction of Mn${}^{3+}$ to

Mn${}^{2+}$, but not as easy as the reduction of Cr${}^{3+}$ to Cr${}^{2+}$. Hence, Fe${}^{3+}$ is more stable than

Mn${}^{3+}$, but less stable than Cr${}^{3+}$. These metal ions can be arranged in the increasing

order of their stability as: Mn3+ < Fe${3+}^{}$< Cr${}^{3+}$

(ii) The reduction potentials for the given pairs increase in the following order.

Mn${}^{2+}$ / Mn < Cr${}^{2+}$ / Cr < Fe${}^{2+}$ /Fe

So, the oxidation of Fe to Fe${}^{2+}$ is not as easy as the oxidation of Cr to Cr${}^{2+}$ and the oxidation

of Mn to Mn${}^{2+}$. Thus, these metals can be arranged in the increasing order of their ability

to get oxidised as: Fe < Cr < Mn