H2SO4 + 2NaOH → Na2SO4 + 2H2O
Concordant titres: 26.15 cm3 and 26.25 cm3
Mean titre: (26.15+26.25)/2= 26.2 cm3/1000= 0.0262 dm3
moles of NaOH: (25/1000)*0.1= 0.0025 mol
Ratio of H2SO4: NaOH= 1:2
Moles of H2SO4: 0.0025/2= 0.00125 mol
Concentration of H2SO4: 0.00125/0.0262= 0.0477 mol dm-3