Nan experiment, chemists heated a solid, red substance in a test tube. vapors from the heated red substance condensed as a metallic liquid on the side of the tube. the red substance eventually disappeared, leaving only the metallic liquid and producing a gas that escaped from the tube. which statement best describes what happened to the red substance in this experiment? a. the experiment demonstrates the formation of plasma from the red substance. b. the experiment demonstrates a physical property of the red substance. c. the experiment shows that the red substance experienced a chemical change. d. the experiment shows that the red substance can be a solid, liquid, or gas. e. the experiment shows that the red substance is an element.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.