Properties of Group 13 Element with Electronegativity of Germanium

To determine the correct statements, we first identify the element '$\text{E}$' based on its electronegativity value on the Pauling scale.

Step 1: Identification of Element '$\text{E}$'

According to the Pauling scale of electronegativity (rounded to one decimal place):

• Group 14 element: Germanium ($\text{Ge}$) has an electronegativity value of $1.8$.
• Group 13 elements:
  • Boron ($\text{B}$) = $2.0$
  • Aluminium ($\text{Al}$) = $1.5$
  • Gallium ($\text{Ga}$) = $1.6$
  • Indium ($\text{In}$) = $1.7$
  • Thallium ($\text{Tl}$) = $1.8$

Since element '$\text{E}$' belongs to Group 13 and has the same electronegativity as $\text{Ge}$ ($1.8$), element '$\text{E}$' is Thallium ($\text{Tl}$).

---

Step 2: Evaluation of the Statements for $\text{Tl}^{3+}$

1. Statement A & B (Oxidizing vs. Reducing agent):

   • Due to the inert pair effect (the reluctance of the $6s^2$ electrons to participate in bond formation), the $+1$ oxidation state ($\text{Tl}^+$) is significantly more stable than the $+3$ oxidation state ($\text{Tl}^{3+}$).
   • Consequently, $\text{Tl}^{3+}$ readily gains two electrons to get reduced to the more stable $\text{Tl}^+$: $\text{Tl}^{3+} + 2e^- \longrightarrow \text{Tl}^+$
   • Thus, $\text{Tl}^{3+}$ acts as a strong oxidizing agent (Statement B is correct; Statement A is incorrect).

2. Statement C (Relative stability of $\text{E}^{3+}$ and $\text{E}^+$):

   • Owing to the pronounced inert pair effect at the bottom of Group 13, $\text{Tl}^+$ is more stable than $\text{Tl}^{3+}$.
   • Thus, statement C, which claims $\text{E}^{3+}$ is more stable than $\text{E}^+$, is incorrect.

3. Statement D (Standard electrode potential $E^\circ(\text{E}^{3+}/\text{E})$):

   • The standard reduction potential values for Group 13 elements ($\text{M}^{3+}/\text{M}$) are:
     • $E^\circ(\text{Al}^{3+}/\text{Al}) = -1.66\text{ V}$
     • $E^\circ(\text{Ga}^{3+}/\text{Ga}) = -0.56\text{ V}$
     • $E^\circ(\text{In}^{3+}/\text{In}) = -0.34\text{ V}$
     • $E^\circ(\text{Tl}^{3+}/\text{Tl}) = +0.72\text{ V}$
   • Hence, the standard electrode potential value for $\text{Tl}^{3+}/\text{Tl}$ is positive ($+0.72\text{ V}$). Statement D is correct.

---

Conclusion

The correct statements are B and D Only.

Correct Option: C (B and D Only)