Consider the following elements In, Tl, Al, Pb, Sn and Ge. The most stable oxidation states of elements with highest and lowest first ionisation enthalpies, respectively, are

Core Logic

Let us check the trends for the provided main group elements (Al, In, Tl$\mathrm{Al, In, Tl}$ from Group 13 and Ge, Sn, Pb$\mathrm{Ge, Sn, Pb}$ from Group 14):

• Highest First Ionization Enthalpy (IE₁$\mathrm{IE}_1$): Out of these options, Germanium (Ge$\mathrm{Ge}$) sits highest and further right along its period layout, demonstrating the highest IE₁$\mathrm{IE}_1$ value among this set. Its most stable oxidation state is +4$+4$.
• Lowest First Ionization Enthalpy (IE₁$\mathrm{IE}_1$): Indium (In$\mathrm{In}$) lies lowest leftward among these relative coordinates, maintaining the lowest IE₁$\mathrm{IE}_1$. Its most stable group oxidation state is +3$+3$ (as the inert pair effect is much more pronounced for the heavier element Tl$\mathrm{Tl}$ which prefers +1$+1$).

Pattern Recognition

Sees: IE₁$\mathrm{IE}_1$ extrema vs stable oxidation state profiles. Trap: Forgetting that inert pair shifts display max stability values at +1$+1$ for Tl$\mathrm{Tl}$ and +2$+2$ for Pb$\mathrm{Pb}$, while lighter counterparts like In$\mathrm{In}$ favor +3$+3$ and Ge$\mathrm{Ge}$ favors +4$+4$.

Chapter Mix

Class 11 Chemistry: The p-Block Elements Class 12 Chemistry: The p-Block Elements