This is polystyrene.
This is College Physics Answers with Shaun Dychko. The index of refraction equals the speed of light in a vacuum divided by the speed of light in the material. So, that's 2.997 times ten to the eight meters per second divided by 2.012 times ten to the eight meters per second, giving an index of refraction of 1.490. I'm looking at the table 12.1 giving us index refractions of different materials. This is polystyrene.