The electronic configuration of $\mathrm{Cu}\left(\mathrm{II}\right)$ is $3{\mathrm{d}}^9$ whereas that of $\mathrm{Cu}\left(\mathrm{I}\right)$ is $3{\mathrm{d}}^{10}$. Which of the following is correct?

Metallic radii of some transition elements are given below Which of these elements will have the highest density?

Which of the following reactions are disproportionation reactions?

${\mathrm{Cu}}^{+}⟶{\mathrm{Cu}}^{2+}+\mathrm{Cu}$

$3{\mathrm{MnO}}_4^{2-}+4{\mathrm{H}}^{+}⟶2{\mathrm{MnO}}_4^{-}+{\mathrm{MnO}}_2+2{\mathrm{H}}_2\mathrm{O}$

$2{\mathrm{KMnO}}_4⟶{\mathrm{K}}_2{\mathrm{MnO}}_4+{\mathrm{MnO}}_2+{\mathrm{O}}_2$

$2{\mathrm{MnO}}_4^{-}+3{\mathrm{Mn}}^{2+}+2{\mathrm{H}}_2\mathrm{O}⟶5{\mathrm{MnO}}_2+4{\mathrm{H}}^{+}$