Question

Which of the answer choices correctly identifies a scenario that displays evidence a chemical reaction is occurring?
Paper absorbs liquid and sinks.
Sugar burns and turns black.
Water boils and evaporates.
Glass vibrates and shatters.

Answer 1

Sugar burns and turns black. A completely new substance was formed, which is the main pointer for it being a chemical reaction. More evidence would be change of color, odor, and the fact that flammability is a chemical property so setting something on fire would be a chemical change.

Answer 2

Answer: Option (b) is the correct answer.

Explanation:

A chemical reaction is the one in which there occurs change in the chemical composition of a substance in order to result in the formation of a new compound.

For example, when sugar burns then it means it is chemically reacting due to which it turns into black.

On the other hand, a physical change is the one in which there occurs no change in chemical composition of a substance. As a result, no new compound is formed.

For example, Paper absorbs liquid and sinks, Water boils and evaporates, and  Glass vibrates and shatters are all physical changes.

Thus, we can conclude that sugar burns and turns black correctly identifies a scenario that displays evidence a chemical reaction is occurring.