Which of the following reactions are disproportionation reactions?
`(A)" " Cu^(+)rarrCu^(2+)+Cu`
`(B)" "3 MnO_(4)^(2-)+4H^(+)rarr2MnO_(4)^(-)+MnO_(2)+2H_(2)O`
`(C )" "2KMnO_(4)rarrK_(2)MnO_(4)+MnO_(2)+O_(2)`
`(D)" "2MnO_(4)^(-)+3Mn^(2+)+2H_(2)O rarr5MnO_(2)+4H^(+)`

Options

A. (i) and (iv) only
B. (i) and (ii) only
C. (i),(ii) and (iii)
D. (i),(iii) and (iv)

Answer

B

Explanation

(i) `2Cu^(+)rarrCu^(2+)+overset(0)(Cu)`
(ii) `overset(+8)MnO_4^(2-)+4H^(+)rarr2overset(+7)MnO_4^(-)+overset(+4)MnO_2+2H_2O`
(iii) `2Koverset(+7)MnO_4overset(Delta)rarroverset(+6)MnO_4+overset(+4)MnO_2+O_2`
`" "("Not disproportionation")`
`2overset(+7)MnO_(4)^(-)+3overset(+2)Mn^(2+)+2H_2Orarr5oversetMnO_2+4H^(+)`
`" "("Not disproportionation")`