Question

Scientists are studying how substance A and substance B react. When substance A and B are mixed, a substance different from A and B floats to the top of the solution. This is evidence that a(n)

Question 6 options:


a. chemical change occurred.


b. irreversible change occurred.


c. endothermic change occurred.


d. physical change occurred.

Answer 1

This is evidence that a. a chemical change occurred.

Substances A and B must have changed into the new substance with new properties. That’s a chemical change.

The reaction could be reversible (A + B ⇌ product) or irreversible (A + B → product). WE can’t tell just by looking at the reaction.

The question didn’t say whether heat was absorbed or evolved, so we don’t know if the reaction is endothermic or exothermic.