Given below are the half-cell reactions,          Mn2++2e−⟶Mn;E∘=−1.18eV2Mn3++e−⟶Mn2+;E∘=+1.51eVThe E∘ for 3Mn2+⟶Mn+2Mn3+ will be

If Ecello is positive, reaction is spontaneous, otherwise it is non-spontaneous.                 Mn2++2e−⟶Mn;E∘=−1.18V         2Mn2+⟶2Mn3++2e−;E∘=−1.51V         3Mn2+⟶Mn+2Mn+3                E∘=Eoxi∘+Ered∘=−1.51+(−1.18)=−2.69VNegative Ecello of the reaction indicates that reaction is non-spontaneous.