Your ears pop when you ascend in an airplane because a
Your inner ear holds air at higher atmospheric
pressure than the air outside your ear
b
The air inside your ear is pushed through to
equalize the pressure
C. Your inner ear holds air at a lower atmospheric
pressure than the air outside your ear
d A & B

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.

i'm assuming that the correct answer is indeed the first one/ "a"..

b.final