sqdancefan

Answer:

7. 1.56

8. A curved line that slopes upward

Explanation:

7. The curve for quartz at the left side of the graph (400 nm) is just above the middle of the distance between 1.5 and 1.6, so is best approximated by 1.56.

___

8. The graph shows n vs. wavelength. The question asks about n vs. frequency. Frequency is inversely proportional to wavelengh, which means you need to describe the curve from right to left, rather than left to right. From right to left, the curve rises, so can be called "a curved line that slopes upward."