{"knowledge_schema": {"broad_category": "Chemistry \u2192 Analytical Chemistry \u2192 Mass Spectrometry", "refinement": "This problem involves identifying a chemical compound based on its mass spectrum data, specifically focusing on the molecular ion peak.", "specific_scope": "The task is to analyze the mass spectrum of an unknown white powder to determine which of the given candidates corresponds to the observed molecular ion peak at m/z = 156.", "goal": "Identify the correct chemical compound from the list of candidates based on the mass spectrum data."}, "summary": "In this problem, we are using mass spectrometry to identify an unknown white powder by analyzing its molecular ion peak. The mass spectrum indicates a peak at m/z = 156, which corresponds to the molecular weight of the compound. The candidates provided are different halogenated benzoic acids. The goal is to determine which compound matches the observed molecular ion peak, leading to the identification of the unknown substance."}