Students observed rust forming on a bar of pure iron. Which of the following provides evidence that the change to the iron bar was a chemical change?The melting point of pure iron is approximately 1,500C. The mass and the volume of the rust can be measured. The iron bar is able to conduct electricity even after rust forms. The rust is a new substance that is not pure iron.

Pegmatites are igneous rocks in which the individual minerals are very large. typically, the minerals are all light-colored quartz, feldspar and muscovite. if you were given a black and white photograph of a pegmatite in a quarry (where the rock has been blasted and broken), what physical properties could you use to identify those three minerals in this hypothetical photo? describe each mineral and the specific diagnostic properties. be specific.