6. Which of these is NOT true of chemical changes?
A. Chemical changes are state changes.
B. Chemical changes can produce heat.
C. A chemical change is a change in composition of a substance.
D. The rearrangement of chemical bonds is a characteristic of chemical changes.
E. Chemical changes result in new substances being formed.
7. What kind of change, chemical or physical, is taking place when a shiny, silvery, iron nail turns reddish-brown when left exposed to the weather? Explain.