what are the only two functional groups that are not able to be categorized by the solubility tests in today's qualitative analysis

The answer is c - the principal of original lateral continuity. 

Ithink that one is (c)

In reversible reaction chemistry equilibrium is attained when the forward and reverse reactions are taking place at the same rate, thus, the concentrations of reactants and products remain the same. a reversible reaction is a chemical reaction where the reactants form products that, in turn, react together to give the reactants back. in irreversible reactions on the other hand, the reactants react to form the products, which cannot revert back into reactants.