Question

For standardizing NaOH solution, which of the following is used as a primary standard ?

• A. Ferrous Ammonium Sulfate
• B. dil. HCl
• C. Oxalic acid
• D. Sodium tetraborate

Answer 1

Answer: (C)

Oxalic acid

Answer 2

The solution that can be prepared directly by dissolving an accurately weighed amount of the substance in water and making up the volume to a known amount by water is known as primary standard solution. Oxalic acid is an example of primary standard while $NaOH$ is a secondary standard solution. Hence, strength of $NaOH$ solution can be determined by titrating against oxalic acid. This process is known as standardisation.