1. Briefly explain what determines the characteristic color of (a) a metal and (b) a trans- parent nonmetal.
2. Briefly explain why some transparent materials appear colored while others are color- less.
3. Briefly describe the three absorption mechanisms in nonmetallic materials.
4. Briefly explain why amorphous polymers are transparent, while predominantly crys- talline polymers appear opaque or, at best, translucent.