This is two seperate answers 1.What is the relationship between an object’s height above the ground and its gravitational potential energy?

2.Move the ball from side to side (left to right) while trying to keep it at the same height. How does changing the horizontal position of the ball affect its potential energy?

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.

let that person have a turn to speak : )