In this task, you are given a question and answer options for that question. Using this information, you have to classify each text into different topics: medicine, nursery, psychology, chemistry, pharmacology, biology.
Q: Question: If we value 25 mL of an H2A acid in concentration 0.1000M (pKa1 = 5, pKa2 = 9) with NaOH, the pH when we have evaluated 50% of the initial acid will be:
Options: <0> one. <1> 3. <2> 5. <3> 7 <4> 9
A:
chemistry