Answer:
5. dispersion
6. 49.8°
Step-by-step explanation:
5. Dispersion is the name given to the phenomenon of light of different wavelengths being bent differently. A rainbow is the result of light from a point source (the sun) being spread out by wavelength (color), a nice example of dispersion.
___
6. n = 1.31 is the ratio of the sine of the angle of refraction to the sine of the angle of incidence (for light passing to a medium of n = 1). When the angle of refraction is 90°, the angle of incidence is the "critical angle." So, ...
sin(90°)/sin(critical) = 1.31
critical angle = arcsin(1/1.31) ≈ 49.8°