The highest level of scientific experiment is known as experimental, or randomized control. In this type, as the name implies, there is the greatest amount of control. There are at least two groups used in this type of scientific experiment. Each group is made up of subjects that resemble each other as close as possible, such as by age, gender, etc. Subjects can be human, animal or the environment.
Chemical changes can result from the combination of different substance through a reaction to give one or more different substances. Decomposition, the opposite of combination, involves the breakdown of a single substance into two or more different substances.
During a chemical change, the composition of the substance is changed. When a chemical change occurs new substances are formed through a reorganization of the atoms. A chemical change is irreversible. An example of chemical change is the fireworks explosion. Chemical Changes are also called Chemical Reactions. The chemical reaction produces one or more products, which usually have properties different from the reactants and have different physical and chemical properties.