Is the rainbow example of total internal reflection?

Answer 1

No. In fact, "total" internal reflection of sunlight is impossible inside a spherical raindrop.

Rainbows are caused by the combined effects of refraction and (not "total") internal reflection, which concentrates the light near deflection angles of 40 to 42 degrees. Since each color is concentrated at a slightly different angle, we see arcs of color at the angles where each color is most intense.

Snell's Law of Refraction says that the angle between the light and the surface normal is greater in the thinner medium (air) than the denser one (water). "Total" internal reflection occurs when light tries to exit the denser medium, but can't because the angle it would have to exit at is greater than 90 degrees. But this can't happen in a spherical water droplet, because the interior angle is always the same every time it hits, or reflects from, the surface.