The rate of a reaction is measured by how fast a reactant is used up or how fast a product is formed.
true or false?

This statement is true. The rate of the reaction is measured by how fast a reactant is used up, or how fast a product is formed. This all tie's into the usage of energy. 

Answer    "a salt" would be the best answerexplanationsalts can be defined as ionic compounds that are neither acids nor bases. nacl is an example of a salt, and its ionic.an enzyme is an organic compound which is covalently bonded, not ionically bonded.acids are generally held together by covalent bondsan element does not need any bonds to exist

Naoh + hbr -> nabr (salt) + h2o ca (oh)2 + 2hbr - - - > ca (br)2 + 2h2o