A 6.50-g sample of a diprotic acid requires 137.5 mL of a 0.750 M NaOH solution for complete reaction. Determine the molar mass of the acid. Additionally, citric acid, which can be obtained from lemon juice, has the molecular formula C6H8O7. A 0.250-g sample of citric acid dissolved in 25.0 mL of water requires 37.2 mL of 0.105 M NaOH for complete neutralization. What number of acidic hydrogens per molecule does citric acid have?