The study of what things are made of and the ways they change

Sorry i dont understand the question can you rephase it?

B. a graduated substance

☆ionisation energy increases across a period from na -> ar☆ionisation energy decreases down a group from li -> fr☆ionic radius decreases across a period from na -> cl☆ionic radius increases down a groupfrom f -> ii hope it clarifies your doubts

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