Question

select the correct answer. in an 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.

Explanation:

• Option A: Plasma formation needs extreme conditions (like very high temp), not just heating a solid to get vapor/liquid/gas, so A is wrong.
• Option B: A physical property is a characteristic without changing substance identity. Here, new substances (metallic liquid, gas) are formed, so it's not a physical property demonstration, B is wrong.
• Option C: A chemical change involves forming new substances. The red solid became a metallic liquid and a gas (new substances), so this is a chemical change. C is correct.
• Option D: The red substance was a solid, then vapor (gas) condensed to liquid, but the key is new substances formed (chemical change), not just state changes of the same substance. So D is wrong.
• Option E: An element can't be broken down into simpler substances by chemical means. Here, the red substance broke down into a metallic liquid and gas, so it's a compound, not an element. E is wrong.

Answer:

C. The experiment shows that the red substance experienced a chemical change.