The electronegativity of a group 13 element 'E' is same as that of...

The electronegativity of Ge on the Pauling scale is $1.8$. In Group 13, the electronegativity values are B ($2.0$), Al ($1.5$), Ga ($1.6$), In ($1.7$), and Tl ($1.8$). Thus, the element 'E' is Thallium (Tl).

Due to the inert pair effect, the $+1$ oxidation state is much more stable than the $+3$ oxidation state for the heavier elements of Group 13, especially Thallium. Therefore, $Tl^+$ is more stable than $Tl^{3+}$. This makes statement C incorrect.

Since $Tl^{3+}$ is relatively unstable, it readily accepts two electrons to form the more stable $Tl^+$ ion ($Tl^{3+} + 2e^- \rightarrow Tl^+$). Because it undergoes reduction easily, $Tl^{3+}$ acts as a strong oxidizing agent. This makes statement A incorrect and statement B correct.

The standard electrode potential for the reduction of $Tl^{3+}$ to Tl ($E^{\circ}_{Tl^{3+}/Tl}$) is $+1.26\text{ V}$, which is a positive value. This makes statement D correct.

Therefore, only statements B and D are correct.