Question
In the preparation of $$KMn{O_4}$$ pyrolusite $$\left( {Mn{O_2}} \right)$$ is first converted to potassium manganate $$\left( {{K_2}Mn{O_4}} \right).$$ In this conversion, the oxidation state of manganese changes from
A.
+1 to +3
B.
+2 to +4
C.
+3 to +5
D.
+4 to +6
Answer :
+4 to +6
Solution :
In $$Mn{O_2}\left( {O.S.\,\,{\text{of}}\,\,Mn\,\,{\text{is}}\, + 4} \right)\,$$ in $${K_2}Mn{O_4}\left( {O.S.\,\,{\text{of}}\,\,Mn\,\,{\text{is}}\, + 6} \right).$$ Hence $$O.S.$$ changes by 2.