The reason for this is that <span>these two ketones are so small that they have only one possible ketone. So the number is usually omitted. Normally the ketone group needs a number but these two are exceptions</span>
The answer is 1. chemical change.
That is when one substance changes into one or more new substances, it has exhibited a chemical change.
A Chemical change is a change that takes places when a substance changes its composition by forming one or more new substances. As here also, one substance is changing into one or more new substance, thus it exhibits a chemical change.
IDensity is calculated by mass divided by volume. As you half the Hershey bar, mass and volume change by the same proportion. Therefore, density is the same.