Numerator and denominator are Equal to one another?
I don’t get the concept

It's like saying that if 1 meter is equal to 100 cm,

or

You can base the answers from the chart

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

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

it should have an internal chamber and two thermometers sticking out of the top. the internal chamber will also be closed off from the outside.