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A black are [x]on fraiment Na(2)CO(3) in...

A black are [x]on fraiment `Na_(2)CO_(3)` in the presence of air gives a green compound (a). When Rreen compound (a) died in water it producess dark precipitate (b) and pink solution (e) crystal of (e) when treated with propene produces dark ppr (b)
Metal present in ore extracted by

A

electrolytic method

B

cyanide process

C

thermite process

D

self reduction

Text Solution

Verified by Experts

The correct Answer is:
C
`underset((x))(2MnO_(2))2K_(2)CO_(3)+O_(2) to 2K_(2)MnO_(4)+2CO_(4)`
The dark green `K_(2)MnO_(4)` disproportionates in a neutral or acidic solution to give permangante.
`3MnO_(4)^(-2)+4H^(o+) to underset((c))(2MnO_(4)^(-))+ underset((b))(MnO_(2))+2H_(2)O`
`MnO_(2)` is dark precipitate (b)
and `KMnO_(4)` solution is pink solution (c)
When `KMnO_(4)` reacts with propene (unsaturated compounds) it is reduced to `MnO_(2)` (b)
`CH_(3)-CH-=CH_(3) overset("Cold" KMnO_(4)//OH^(-))toCH_(3)- underset(OH) underset(|)(CH)- underset(OH) underset(|)(CH_(2)) underset((b))(MnO_(2))`
The metal present in ore `X(MnO_(2))` is n which is extracted by thermite process.
`3Mn_(3)O_(4)+8Al to 9 Mn+4Al_(2)O_(3)` heat
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