Which compound amongst the following gas the highest oxidation number of Mn?
`KMnO_(4), K_(2)MnO_(2), MnO_(2) and Mn_(2)O_(3)`

Explanation

`KMnO_(4) +1+x-8=0`
Ox. No. of Mn x=+7 +7
`K_(2)MnO_(4)" +2+x-8=0" "x=+6" "+6`
`MnO_(2)" "x-4=0" "x=+4" "+4`
`Mn_(2)O_(3)" "2x-6=0" "x=+3" "+3`
Thus, the higest oxidation number for Mn is in `KMnO_(4)`.
Sometimes, oxidation numbers have such values which at first sight appear strange. For example the oxidation number of carbon in cane sugar `(C_(2)H_(22)O_(11)), " glucose "(C_(6)H_(12)O_(6)),` dichloromethane, etc., is zero.
Cane sugar `(C_(12)H_(22)O_(11))" Glucose "(C_(6)H_(12)O_(6))`
`12 xx x+22 xx 1+11 (-2)=0`
`6 xx x +12 xx 1+6(-2)=0`
12+22 -22=0
6x+12-12=0
So x=0
Dichloromethane `(CH_(2)Cl_(2))`
`x+2 xx 1+2(-1)=0`
x+2-2=0
So x=0