In the reaction h2so4 + 2 naoh -> na2so4 + 2h2o, an equivalence point occurs when 24.34 ml of 0.2123 m naoh is added to a 26.05 ml portion of h2so4. what is the [h2so4]?

The reaction H2SO4 + 2 NaOH -> Na2SO4 + 2H2O applies to an acid-base titration. We are calculating the [H2SO4].
            moles NaOH = c · V = 0.2123 mmol/mL · 24.34 mL = 5.167382 mmol
            moles H2SO4 = 5.167382 mmol NaOH · 1 mmol H2SO4 / 2 mmol NaOH = 2.583691 mmol
Hence
            [H2SO4]= n/V = 2.583691 mmol / 26.05 mL = 0.09918 M
The answer to this question is  [H2SO4] = 0.09918 M