Answer:
According to the law of conservation of mass, the masses of the products and reactants must be the same. Adding calcium to the product side is considered a mistake if it is not in the reactant side of a particular chemical equation because it is impossible to produce calcium from thin air (unless this is a nuclear reaction).
Explanation:
Which of the following describes a nuclear stress test?
a. the heart's electrical signals are traced with each heartbeat.
b. blood is drawn from an artery instead of a vein.
c. sound waves are used to see the heart.
d. a radioactive substance is injected into the bloodstream.