Sedimentary rocks don't necessarily make fossils. Although when animals die on top of the rocks and are never moved, blown away, etc they can get trapped under the growing rock. Which is why fossils are often found in sedimentary rocks.
Answer:
n Al= 10/27( mol)- >n Al2O 3 =5/27(mol)
Explanation:
Yep. And you'll always get equations with units that don't match