A dichotomous key is an important scientific tool, used to identify different organisms, based the organism's observable traits. Dichotomous keys consist of a series of statements with two choices in each step that will lead users to the correct identification.
Answer:
C. substances that are used up in a reaction
Explanation:
Substances are combined in a chemical reaction to give rise to other substances. The substances that come together are called REACTANTS while the substances that are produced are called PRODUCTS.
Reactants are used up in the reaction to give rise to new products at the end of the reaction. For example, in the reaction as follows:
6CO2 + 6H2O --> C6H12O6 + 6O2
CO2 (carbon dioxide) and water (H2O) are the REACTANTS of the reaction, which are used up to form glucose and oxygen (products)
