Question 11

Let us say  x moles of formic acid and y moles of oxalic acid  are present in the mixture.
Balanced equations are :
x HCOOH  ----> xCO + H2O
  yH2C2O4 ----> yCO +yCO2 + yH2O
H2O is absorbed by H2SO4
when we add KOH ,CO2 reacts with it and CO2 is also absorbed.
Molar ratio is also volume ratio of these gases as they are at the same temperature and pressure.
If total Volume before KOH addition is V
then Volume left after KOH addition is 5V/6
we can say
x + 2y = V (before addition of KOH)
x+y = 5V/6 (after absorption of y moles of CO2)
solve it for x and y in terms of V and take the ratio.