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.
Chemical Change - the result of a reaction which creates one of more substances with different chemical properties. Chemical Property - the chemical traits of matter or the potential of matter to react in a particular way. Matter - any object or substance that 1) takes up space and 2) has mass. Physical Change - a visible, quantifiable, generally reversible alteration of the physical state of matter. Physical Property - the corporeal definition of matter, a description of the state of a particular matter.