Mn(III) in water disproportionates: $2\mathrm{Mn}{}^{3+}+2\mathrm{H}{}_2\mathrm{O}\to \mathrm{Mn}{}^{2+}+\mathrm{MnO}{}_2+4\mathrm{H}{}^{+}$. Which statements are correct?

1. A$\mathrm{Mn}{}^{2+}$ formed has five unpaired electrons.
2. BThe reaction is a disproportionation of Mn(III) into Mn(II) and Mn(IV).
3. CManganese in $\mathrm{MnO}{}_2$ is $3d^4$.
4. D$\mathrm{Mn}{}^{3+}$ is $3d^4$, so high-spin $\mathrm{Mn}{}^{3+}$ has $\mu =4.90\mathrm{BM}$.