[填空题]
Oxygen and water are7sme6ya6 j8 0abvly b7 produced whew 0t*5vp w)alen nitric acid reacts with potassium manganate(VII)5wa 0wt p)e*vl,$KMnO_4$.
$4KMnO_4(aq) + 12HNO_3(aq) \rightarrow 6H_2O(I) + 5O_2(g) + 4KNO_3(aq) + 4Mn(NO_3)_2(aq)$
1.Define reduction in terms of electron transfer.
2.State the oxidation state of manganese in $KMnO_4$ and in $Mn(NO_3)_2$.In $KMnO_4$:X= , In $Mn(NO_3)_2$:X=
3.Identify which species has been oxidized in this reaction and specify the change in oxidation state it has undergone.