A 5.0 mL solution of H2O2 liberates 1.27 g of iodine from an acidified KI solution. The percentage strength of H2O2, is

H2O2≡KI≡I2mEq of H2O2=5×NmEq of I2= Weight Ew×1000 =1.27127×1000=10mEqI2=Mw=254 Ew =Mw2=2542=127∴mEq of H2O2=mEq of I25×N=10 ∴ N=21N of H2O2=1.7%H2O22N of H2O2=3.4%H2O2