Lowering an object decrease is potential

Lowering the object near the ground decreases its potential energy.

Explanation:

Potential Energy : Energy possessed by the object due to its shape ,Size and Position is called potential energy.

Example :

Change in shape and size :  When  you compress the spring , potential energy is introduced in it . So it expand quickly when you remove your hand.

Change in position : when you swing , after attaining maximum height (extreme ends) , the swing comes back on its on .This is because at maximum height ,the swing has maximum Potential energy . Hence it fall back on its on because it already has potential energy.

Potential energy(P) is given by the formula :

P = mgh

where ,

m= mass of the object

g = acceleration due to gravity

h = height of the object from the ground

If the height of the object increases from the ground , its potential energy also get increase.

On lowering the object The height of the object from the ground reduces . So potential energy also reduces.

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.