Dark Stool: If your stool is black or bright red in color, it can mean that you are bleeding internally, as a possible result of an ulcer or cancer, and warrants a call to your doctor even if you think it could be hemorrhoids, or tiny tears in the anal tissue, due to constipation and straining.
The chemical reaction in which high molecular mass molecules are formed from monomers is known as polymerization. There are two basic types of polymerization, chain-reaction (or addition) and step-reaction (or condensation) polymerization.
A chemical reaction produces a chemical change as atoms are rearranged resulting in the production of one or more new substances. In all chemical reaction there is a conservation of mass. Atoms are neither created nor destroyed. Chemical reactions are generally difficult to reverse. eg.