This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': '1 equivalent of Ca2+ ion is equal to: \nSelect and explain. \nA. 10 gram, B. 20 gram, C. 30 gram, D. 40 gram', 'role': 'user'}, {'content': "Answer: B \nExplanation: The concept of electrical equivalence is impoant in physiology because many of the solutes in the body are in the form of charged paicles. One equivalent (eq) is 1 mol of an ionized substance divided by its valence. One mole of NaCl dissociates into 1 eq of Na+ and 1 eq of Cl-. One equivalent of Na+ = 23 g, but 1 eq of Ca2+ = 40 g/2 = 20 g. The milliequivalent (meq) is 1/1000 of 1 eq. Ref: Ganong's Review of Medical Physiology 23rd edition, Chapter 1.", 'role': 'assistant'}]