A disproportionation reaction is an oxidation-reduction reaction in which the same substance is oxidized and reduced. Complete and balance the following disproportionation reactions.

1)Ni+(aq)→Ni2+(aq)+Ni(s) (acidic solution)
2)MnO42−(aq)→MnO4−(aq)+MnO2(s) (acidicsolution)
3)H2SO3(aq)→S(s)+HSO−4(aq) (acidicsolution)
4) Cl2(aq)→Cl−(aq)+ClO−(aq) (basicsolution)
Express your answer as a chemical equation including phases.