At a temperature of 80°C, 100 g of Ba(OH)2 are completely dissolved in 100 mL of water. If the solution is cooled to about 62°C, how many grams will come out of the solution because

they can no longer be dissolved?

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.

b.false that your answer