The eivalent weight of oxalic acid is

The equivalent weight of an acid is calculated by dividing its molecular mass by its basicity, which is the number of replaceable hydrogen ions per molecule. Oxalic acid is a diprotic (dibasic) acid, meaning it can donate two protons (H+) per molecule. In laboratory settings, oxalic acid commonly exists in its hydrated form as crystalline oxalic acid dihydrate (H2C2O4·2H2O). The molar mass of anhydrous oxalic acid is approximately 90 g/mol, leading to an equivalent weight of 45. However, the standard analytical reagent used in titrations is the dihydrate form, which has a molar mass of approximately 126 g/mol. Dividing this molar mass by its basicity (126 / 2) results in an equivalent weight of 63. Given the options provided, 63 is the standard value used in chemistry for oxalic acid equivalent weight calculations.