The skin cells of a scorpion organize together to make a hard covering called a carapace, which protect the scorpion. what is the term for a group of similar cells working together?

The term is tissue.

A tissue in biology is the intermediate level of organization between the cell and the organ. A tissue is a set of similar cells of the same origin, grouped in clusters, network or beam (fiber). A fabric forms a functional whole, that is to say that its cells contribute to the same function. Biological tissues regenerate regularly and are assembled together to form organs.

The science that studies the tissues is histology.

when a reversible reaction is occurring in both directions at the same rate; the products and reactants do not change in concentration. a chemical reaction where the compound is broken into its constituent parts.