1.

Pick out the correct statement(s)

Answer»

`MnO_(2)` dissolves in conc. `HCl`, but does not form `Mn^(4+)` ions
Decomposition of acidic `KMnO_(4)` is not CATALYSED by sunlight
`MnO_(4)^(2-)` is strongly oxidising and stable only in very strong alkalu. In dilute alkali, water or acidic solution it disproportionates
`KMnO_(4)` does not act as oxidising agent in alkaline medium

Solution :(a) `MnO_(2)+4HCl rarr MnCl_(2)+cl_(2)+2H_(2)O`
(b) Decomposition of acidic `KMnO_(4)` is catalysed by sunlight.
`4MnO_(4)^(-)+4H^(+)rarr 4MnO_(2)+2H_(2)O+3O_(2)`
(c) `underset("green")(3K_(2)MnO_(4))+2H_(2)Orarrunderset("purple")(2KMnO_(4)^(-))+underset("dark brown")(MnO_(2)DARR)+4KOH`
(d) `KMnO_(4)` also acts as an oxidizing agent in alkaline medium.
`MnO_(4)^(-)+2H_(2)O+3e^(-)rarrMnO_(2)+4OH^(-),E^(@)=+1.23" volt"`


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