On a warm, pleasant day, you notice some clouds in the sky. The clouds are very high up in the sky and look quite thin. Which type of clouds are in the sky?

Cumulonimbus clouds

Explanation:

"Cumulonimbus clouds grow on hot days when warm, wet air rises very high into the sky. From far away, they look like huge mountains or towers."

https://scijinks.gov/clouds/#:~:text=Cumulonimbus%20clouds%20grow%20on%20hot,like%20huge%20mountains%20or%20towers.

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.

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.