Which statement regarding disproportionation is true based on provided E data?

Disproportionation is a type of redox reaction where a single species is simultaneously reduced and oxidized, resulting in two different products. To determine whether Cu(I) and Hg(I) can undergo disproportionation, we assess their standard reduction potentials (E° values) to see if the conditions for disproportionation are met.

Cu(I) has a known E° value that is favorable for it to be oxidized to Cu(II), while also being reduced to Cu(0). The reverse could also be considered for the respective half-reactions; this favorable energy change indicates that disproportionation can indeed occur with Cu(I).

On the other hand, Hg(I) generally exists in the form of dimers (Hg2^2+) rather than as individual Hg(I) ions, and the conditions do not favor its disproportionation as efficiently as Cu(I). As such, the redox potentials do not support a favorable pathway for Hg(I) disproportionation, positioning it as less likely to undergo this reaction.

In summary, the statement that only Cu(I) can undergo disproportionation is true because the electrochemical properties and standard reduction potentials favor the disproportionation of Cu(I) while not supporting that of Hg(I).