(i) Complete the following equations :
(a) `2MnO_(4)^(-)+ 5SO_(3)^(2-)+6H^(+)to`
(b) `Cr_2O_(7)^(2-)+6Fe^(2+)+14H^(+)to`
(ii) Based on the data, arrange `Fe^(2+), Mn^(2+) and Cr^(2+)` in the increasing order of stability of `+2` oxdiation state .
`E^(@) Cr^(3+)//Cr^(2+)=-0.4V`
`E^(@) Mn^(3+)//Mn^(2+)=01.5V`
`E^(@) Fe^(3+)//Fe^(2+)=+08V`

Explanation

(i)(a) `2MnO_4^(-)+5SO_(3)^(2-)+6H^(+)to 2Mn^(2+)+3H_2O+5SO_(4)^(2-)`
(b) `Cr_2O_7^(2-)to 6Fe^(2+)+14H^(+)to 2Cr^(3+)+6Fe^(3+)+7H_2O`
(ii) `E^(@) Cr^(3+)//Cr^(2+)=-0.4V`
`E^(@) Mn^(3+)//Mn^(2+)=01.5V`
`E^(@) Fe^(3+)//Fe^(2+)=+08V`
Increasing order of stability of `+2` oxidation state is :