Prehospital Emergency Pharmacology Practice Test

Calcium ion is the term that matches Ca2+. The symbol Ca is calcium, and the superscript 2+ shows it has lost two electrons, giving a positively charged ion. In biology and pharmacology, Ca2+ is the active form involved in muscle contraction, nerve signaling, and blood clotting, and is the form often manipulated in prehospital care (for example, calcium salts are used in specific overdoses or electrolyte disturbances). The other options do not represent calcium at all—aspirin is a drug, kilogram is a unit of mass, and BP stands for blood pressure.