A change in which no new products are formed is what kind of charge?
Physical changes are the changes in which no new products are formed. The composition of the material remains the same, however its appearance may change. An example of a physical change is the melting of metals. In this process, as the heat is supplied, the metal (say iron) starts melting, becomes liquid and starts flowing. The phase of the metal has changed, yet it still stays iron and no new material has been formed and the composition has stayed the same. Physical changes are typically directly observable.
In comparison, chemical changes involve changes in chemical composition and new materials are formed. For example, burning of a piece of paper will produce gases (such as carbon dioxide), soot, etc. All these are new materials or compounds and hence represent a change in chemical composition.
Hope this helps.