Comprehensive Study on Physical Changes and Chemical Changes

A physical change is formally defined as a process in which a substance undergoes a transformation that affects only its physical properties.
The most critical distinguishing feature of a physical change is that no new substance is formed during the process. The chemical identity of the matter remains entirely intact and unchanged from its original composition.
While a physical change often results in an observable modification in the appearance of the substance, this is purely superficial in terms of chemical makeup.

In the context of physical changes, the modifications are restricted to specific physical characteristics. These properties include:

Shape: The external form, contour, or outline of the substance may be altered.
Size: The dimensions, volume, or magnitude of the substance may increase or decrease.
State of Matter: This refers to the phase in which a substance exists. A change from one state to another (such as a transition between solid $(s)$ , liquid $(l)$ , or gas $(g)$ ) is classified as a physical change because the underlying molecular or atomic structure of the substance does not transition into a different chemical entity.

When evaluating a transformation, the observer must determine if the internal structure of the material has been rearranged to create a different substance. If the identity is preserved, it is categorized strictly as a physical change.
Observational evidence of a change in appearance is not sufficient to indicate a chemical transformation; rather, the focus must remain on whether the identity and properties of the internal matter have stayed the same.
Understanding physical changes serves as the precursor to exploring more complex transformations where the fundamental nature of the substance is altered into something entirely different.