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Question
Explain why does colour of \[\ce{KMNO4}\] disappear when oxalic acid is added to its solution in acidic medium.
Solution
\[\ce{KMnO4}\] acts as oxidising agent. It oxidises oxalic acid to \[\ce{CO2}\] and itself changes to \[\ce{Mn^2+}\] ion which is colourless.
\[\ce{5C2O^{2-}4 + \underset{(Coloured)}{2MnO^-4} + 16H+ -> \underset{(Coloured)}{2Mn^2+} + 8H2O + 10CO2}\]
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| List - I | List - II | ||
| (a) | \[\ce{[Fe(CN)6]^3-}\] | (i) | 5.92 BM |
| (b) | \[\ce{[Fe(H2O)6]^3+}\] | (ii) | 0 BM |
| (c) | \[\ce{[Fe(CN)6]^4-}\] | (iii) | 4.90 BM |
| (d) | \[\ce{[Fe(H2O)6]^2+}\] | (iv) | 1.73 BM |
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