I just took a test in school today. What question was I asked?

Question I was asked: A geologist finds a layer of shale near the surface from a certain time period. Nearby, the geologist finds the same layer of shale, but it is deeper underground than the first layer. What might have caused the difference in the depth of the shale layer?

I just took a test in school today. What question was I asked?

Question I was asked: Because sulfur cannot be decomposed by simple chemical methods into two or more different substances, it is classified as

I just took a test in school today. What question was I asked?

Question I was asked:
A solution of lead (II) nitrate reacts with a solution of sodium iodide to produce a yellow solid of lead (II) iodide and aqueous sodium nitrate. Which of these illustrates the reaction?