(a) Complete the following chemical equations for reactions in aqueous media :
(i) `Cr_(2)O_(7)^(2-)+H^(+)+Fe^(2+)to`
(ii) `MnO_(4)^(-)+I^(-)+H^(+)to`
(b) How many unpaired electrons are present in `Mn^(2+)` ion (At. no. of Mn = 25] ? How does it influence magnetic behaviour of `Mn^(2+)` ions ?

Explanation

Completed reactions are given as under :
(a) (i) `Cr_(2)O_(7)^(2-)+14H^(+)+6Fe^(2+)to2Cr^(3+)+6Fe^(3+)+7H_(2)O`
(ii) `2MnO_(4)^(-)+10I^(-)+16H^(+)to 2Mn^(2+)+8H_(2)O+5I_(2)`
(b) `Mn^(2+) : 3d^(5)4s^(0)` has 5 unpaired electrons. It is highly paramagnetic and it is attracted by magnet.