How many mole of electrons are involved balancing the following equations:
(a) `H_(2)S+NO_(3)^(-)rarrS+NO`
(b) `Mn(OH)_(2)+H_(2)O_(2)rarrMnO_(2)+2H_(2)O`
(c ) `Cr_(2)O_(7)^(2-)+Fe^(2+)+C_(2)O_(4)^(2-)rarrCr^(3+)+Fe^(3+)+CO_(2)`
(acid medium)
(d) `Br_(2)+OH^(-)rarrBrO_(3)^(-)+Br^(-)`
(e ) The compound `P_(4)S_(3)` is oxidised by nitrate ions acid medium to give phosphoric acid, sulphate ions and nitric oxide `(NO)`. Write the balanced half reactions and the overall reaction.

Explanation

`{:((a),,S^(2-), rarr ,S^(0) ,+ 2e,),(,N^(+5), + 3e ,rarr ,N^(2+),, 6N "electron"):}`
`{:((b),,Mn^(2+), rarr ,Mn^(4+) ,+ 2e,),(,O_(2)^(1-), + 2e ,rarr ,O_(2)^(2-),, 2N "electron"):}`
( c) `{:((c ),,Cr_(2)^(6-),+3e, rarr, 2Cr^(3+),,3N "electron",,),(,,Fe^(2+), + C_(2)^(3+) ,rarr ,Fe^(3+)+2C^(4+),+3e, ,,):}`
`{:((d),,Br_(2)^(0),+2e, rarr, 2Br^(-),,10 N "electron",,),(,,,Br_(2)^(0), rarr ,2Br^(5+) ,+10e,, ,):}`
(e) `{:((P^(3//2))_(4)rarr4P^(5+)+14e),((S^(2-))_(3)rarr3S^(6+)+24e),(bar([P_(4)S_(3)rarr4P^(5+)+3S^(6+)+38e]xx3)),(ul([3e+N^(5+)rarrN^(2+)]xx38)):}`
`3P_(4)S_(3)+38NO_(3)^(-)rarr12H_(3)PO_(4)+9SO_(4)^(2-)+38NO`
`3P_(4)S_(3)+38NO_(3)^(-)+20H^(+)+8H_(2)Orarr12H_(3)PO_(4)+9SO_(4)^(2-)+38NO`