If a g is the mass of NaHC2O4 required to neutralize 100 mL of 0.2 M NaOH and b g that required to reduce 100 mL of 0.02 M KMnO4 in acidic medium, then:

eq. wt. of NaHC2O4 as an acid =112eq. of NaHC2O4 = eq. of NaOH=100x10-3x0.2=0.02a =0.02 x112 = 2.24 geq. wt. of NaHC2O4 as reductantC2O42−⟶2CO2+2e−=1122=56eq. of NaHC2O4 as reductant = eq. ofKMnO4 = 100 x 10-2 x 0.02 x 5 = 0.01b = 0.01 x 56 = 0.56 gHence, a:b=2.240.56=4:1 or a=4b