Okay, I'm really confused in general.

Question

My question says:
"A solid piece of clear transparent material has an index of refraction of 1.61. If you place it into a clear transparent solution and it seems to disappear, approximately what is the index of the refraction of the solution? How do you know?"

I'm thinking of the use of snell's law to find the approximate index of refraction but I'm confused on the needed angle.

Answer 1

the index of the solution must be approximately the index of the material

there is no refractive boundary between the material and the solution, so the material seems invisible