Evaluate equivalent weight of reductant or oxidant given on left hand side of each reaction:
(a) `As_(2)O_(3)+5H_(2)Orarr2AsO_(4)^(3-)+10H^(+)+4e`
(b) `MnO_(4)^(-)+8H^(+)+5erarrMn^(2+)+4H_(2)O`
(c ) `Cr_(2)O_(7)^(2-)+14H^(+)+6erarr2Cr^(3+)+7H_(2)O`
(d) `C_(2)O_(4)^(2-)rarr2CO_(2)+2e`
(e ) `FeC_(2)O_(4)rarrFe^(3+)+2CO_(2)+3e`
(f) `2CuSO_(4)+2erarrCu_(2)^(1+)+SO_(4)^(2-)`

Explanation

`E_("red"//"oxi")={:(ul("Mol.weight of reductant or oxidant")),("Number of electrons gained or lost by"),("one molecule of reductant or oxidant"),("or valence factor"):}`
(a) `E_(As_(2)O_(3)) =(M_(As_(2)O_(3)))/(4)`
`(As_(2)^(3+) rarr 2As^(5+) + 4e)`
(b) `E_(MnO_($)^(-)) = (M_(MnO_(4)^(-)))/(5)`
`(Mn^(7+) + 5e rarr Mn^(2+))`
( c) `E_(Cr_(2)O_(7)^(2-)) = (M_(Cr_(2)O_(7)^(2-)))/(6)`
`(Cr_(2)^(6+) rarr 2Cr^(3+) + 6e)`
(d) `E_(C_(2)O_(4)^(2-)) = (M_(C_(2)O_(4)^(2-)))/(2)`
`(C_(2)^(3+) rarr 2C^(4+) + 2e)`
(e) `E_(FeC_(2)O_(4)) = (M_(FeC_(2)O_(4)))/(3)`
`(Fe^(2+)+C_(2)^(3+) rarr Fe^(3+) + 2C^(4+) + 3e)`
(f) `E_(CuSO_(4)) = (M_CuSO_(4))/(1)`
`(2Cu^(2+) + 2e rarr Cu_(2)^(+))`