One mole of `SO_(3)` was placed in a two litre vessel at a certain temperature. The following equilibrium was established in the vessel
`2SO_(3)(g)hArr2SO_(2)(g)+O_(2)(g)`
The equilibrium mixture reacts with `0.2` mole `KMnO_(4)` in acidic medium. Hence, `K_(c)` is :

Answer

1