Henry's Law — FRCA Primary MCQ
Instant feedback + full explanation. One question, done properly.
Educational content. Not a substitute for clinical judgement or local policy.
Reveal the answer and explanation
Correct answer: E — The amount of gas dissolved in a liquid is proportional to its partial pressure at constant temperature
Explanation lettering: C = shown as A · E = shown as B · B = shown as C · A = shown as E
Henry's law states that, at equilibrium and constant temperature, the concentration or amount of a gas dissolved in a liquid is directly proportional to the partial pressure of that gas in contact with the liquid: C = alphaP, where alpha is the solubility coefficient. Therefore, A is correct. The law describes physically dissolved gas rather than gas bound to haemoglobin or chemically converted in blood. B describes Charles's law. C is Avogadro's law, more precisely referring to equal volumes containing equal numbers of molecules at the same temperature and pressure. D is Boyle's law. E is Dalton's law of partial pressures.
Reference: Christmas KM, Bassingthwaighte JB. Equations for O2 and CO2 solubilities in saline and plasma: combining temperature and density dependences. Journal of Applied Physiology. 2017;122(5):1313–1320. https://pubmed.ncbi.nlm.nih.gov/28235861/