Identifying Gases in Inspired and Expired Air Pie Charts Steps: - Recall inspired air composition: 78% nitrogen, 21% oxygen, 0.04% carbon dioxide, trace others. - Recall expired air composition: 78% nitrogen, 16% oxygen, 4% carbon dioxide, trace others; nitrogen remains constant, oxygen decreases, carbon dioxide increases. - Compare pie charts: largest segment (likely Segment 3) is nitrogen in both; medium segment (Segment 1) is oxygen (larger in inspired, smaller in expired); smallest (Segment 2) is other gases including CO2. - Match segments: Segment 1 to oxygen, Segment 2 to other gases, Segment 3 to nitrogen. Why B is correct: - Nitrogen is the dominant gas (~78%) in both air types, matching the largest segment (3); oxygen is next (~21% inspired, 16% expired), fitting Segment 1; per respiratory physiology definitions. Why the others are wrong: - A: Misassigns nitrogen to Segment 1 (not the largest) and duplicates "other gases" without specifying oxygen or CO2 changes. - C: Assigns carbon dioxide to Segment 3, but CO2 is minor (~4% max), not the largest segment. - D: Identical to C, incorrectly labeling largest …