Potassium permanganate oxidises oxalic acid in suphuric acid medium to give potassium sulphate, manganous sulphate, carbondioxide and water.

Explanation

a) The skeleton equation is written as
? `KMnO_(4)+H_(2)C_(2)O_(4)+H_(2)SO_(4)rarrK_(2)SO_(4)+MnSO_(4)+CO_(2)+H_(2)O`
b) Focusing on the oxidation numbers
`overset(+1)Koverset(+7)(Mn)overset(-2)(O_(4))+overset(+1)(H_(2))overset(+3)(C_(2))overset(-2)(O_(4))+overset(+1)(H_(2))overset(+6)(S)overset(-2)(O_(4))rarroverset(+1)(K_(2))overset(+6)(S)overset(-2)(O_(4))+overset(+2)(Mn)overset(+6)(S)overset(-2)(O_(4))+overset(+4)(C)overset(-2)(O_(2))+overset(+1)(H_(2))overset(-2)(O)`
c) Locating atoms undergoing change in oxidation numbers
`Koverset(+7)(Mn)O_(4)+H_(2)overset(+3)(C_(2))O_(4)rarrMnoverset(+2)(SO_(4))+overset(+4)(CO_(2))`
d) Determining the change in oxidation numbers

e) Cris - crossing these change in oxidation numbers
`2KMnO_(4)+5H_(2)C_(2)O_(4)rarrMnSO_(4)+CO_(2)`
f) Balancing the atoms other than hydrogen and oxygen
`2LMnO_(4)+5H_(2)C_(2)O_(4)+3H_(2)SO_(4)rarrK_(2)SO_(4)+2MnSO_(4)+10CO_(2)+H_(2)O`
g) Balancing the atoms hydrogen and oxygen
`2KMnO_(4)+5H_(2)C_(2)O_(4)+3H_(3)SO_(4)rarr K_(2)SO_(4)+2MnSO_(4)+10CO_(2)+8H_(2)O`
This is the balanced equation.