Things around us are constantly changing every moment - from the growth of our hair and nails, to the expansion and contraction of our lungs when breathing, to the moon's motion. As a result, our surroundings are continuously changing. Some of these modifications are short-lived, which means we may reverse them, and others are permanent, which means we cannot reverse them. A handful of these changes are hardly visible. Let us look at what such changes are and how these changes occur.
A change is defined as any variation in the form or size of an object. Some changes can often be undone, while others cannot. Changes may be classified into two major groups based on this: reversible and irreversible changes -
(1) Changes that may be undone or reversed are reversible.
Reversible change occurs when you can return to the original material. In the vast majority of situations, new material is not generated due to a reversible transformation. For example, drying clothes, boiling milk, stretching a rubber band, and setting ice. The physical qualities of a substance can alter at any time. When water heats up, for example, it turns into steam.
(2) Irreversible changes cannot be undone or reversed. It is the kind of change you can't undo with any physical or chemical method, regardless of what you do. During this process, new material is usually always created. An example of an irreversible change is the combustion of coal, which results in a chemical change. It is permanent because a new chemical is generated that we can never convert back to coal. Other examples include burning coal to form ash, making curd from milk, grinding grains to form flour, and blooming a flower.
Besides reversible and irreversible changes, there are two further changes to consider: physical and chemical changes.
(1) Physical changes impact a substance's physical qualities but not its chemical properties. For instance, boiling water, freezing water, melting wax, etc.
(2) Chemical changes influence a substance's chemical and physical qualities. For example, food digestion, coal or paper combustion.