Your teacher asks you to follow the instructions in a lab to produce several known chemical reactions. During these procedures,
you are required to record any observations that suggest chemical reactions have occurred. Which of these list of observations best
describes evidence of chemical reactions?
a. a liquid melts and becomes a solid.
b. when heated steam comes out of a test tube.
c. a gas or solid is formed from two liquid solutions.
d. the two chemicals separate and form two distinct layers.