(5 simple questions)
1. which of these is an indication that a chemical reaction has occured?
a. formation of gas
b. freezing of a substance
c. boiling of a substance
d. melting of a substance

2.if the temperature changes in a chemical reaction, what has occurred?
a. energey was destroyed
b. energy was transferred
c. energy was created
d. there was no energy transfer

3.which of these accurately describes the reactants of a reaction?
a. substances that do not participate of a reaction
b. new substances that are present at the end of a reaction
c. substances that are used up in a reaction
d. new substances formed in the reaction

(rest are below)