Final answer:
The subject of this question is Chemistry, specifically the chemical analysis of water used for hemodialysis in a medical setting.
Step-by-step explanation:
The subject of this question is Chemistry. It is asking about the chemical analysis of water used for hemodialysis. Hemodialysis is a medical procedure used to filter waste and excess fluid from the blood when the kidneys are unable to do so. Analyzing the chemical composition of the water used in hemodialysis is important to ensure it is safe and free from contaminants that could harm the patients.