Question

in a synthesis reaction, what happens? a. two or more substances combine to form a single compound. b. a single compound breaks down into simpler substances. c. two elements swap places in different compounds. d. an element replaces another in a compound.

Explanation:

A synthesis reaction is defined as a reaction where two or more substances combine to form a single compound. Option b describes a decomposition reaction, option c describes a double - displacement reaction, and option d describes a single - displacement reaction.

Answer:

A. Two or more substances combine to form a single compound.