Classify the following as physical or chemical changes.
a. Moth balls gradually vaporize in a closet.
b. Hydrofluoric acid attacks glass, and is used to etch calibration marks on glass laboratory utensils.
c. A French chef making a sauce with brandy is able to burn off the alcohol from the brandy, leaving just the brandy flavoring.
d. Chemistry majors sometimes get holes in the cotton jeans they wear to lab because of acid spills.
