If an artificial heart is capable of pumping at least 5.7x10' pints of blood before failure, how long, in years, will it robably last in a patient whose average heart rate is 72 beats per minute and an average stroke volume (the amount
f blood pumped with each beat) is 70 mL?

14 days is the half-life of phosphorus-32

c) should be the answer.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.