Purpose of tanning in the leather industry is toa) stiffen the leatherb) smoother the leatherc)impart water resistance d) make it flexible

d) Make it flexible  

Step-by-step explanation:

Raw hides dry out to form a hard material that can decay with an offensive smell when they become wet.

Tanning converts the protein of the raw hide into a stable material that will stay flexible and not decompose when it gets wet.

a) is wrong. The purpose of tanning is to soften the leather.

b) is wrong. You smooth the leather manually with fine sandpaper.

c) is wrong. Tanning does not impart water resistance. It prevents the leather from putrefying when it does get wet.

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.