Dalton's Law — FRCA Primary MCQ
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Correct answer: D — Dalton's law
Dalton's law of partial pressures states that the total pressure of a mixture of non-reacting gases is the sum of the pressures that each gas would exert if it alone occupied the same volume at the same temperature: P_total = ΣP_i. Thus, option D is correct. Boyle's law describes the inverse relationship between pressure and volume at constant temperature. Charles's law relates gas volume to absolute temperature at constant pressure, whereas Gay-Lussac's law relates pressure to absolute temperature at constant volume. Henry's law concerns the amount of gas dissolved in a liquid and its relationship to the gas's partial pressure above that liquid. These alternatives therefore describe different physical relationships.
Reference: Royal College of Anaesthetists. Guide to the FRCA Examination: The Primary, fourth edition, MCQ answer 45(d), 2013; hosted 2025. https://www.rcoa.ac.uk/sites/default/files/documents/2025-08/RCoAPrimaryGuide2013%20FOR%20WEBSITE.pdf