Why is a shell considered to be biotic​

In biology, a shell is defined as a protective structure of mollusks and crustaceans. A shell is considered to be biotic because it came from something living. Shells are not in fact alive as they are made of calcium carbonate and in some cases α-chitin, two non living materials

Explanation:

the answer is 0.8m.

by: nicholas

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.