Asound wave travels through water in the tank of an aquarium. how do you expect the wave to travel differently when it reaches the thick glass of the side of the tank?
a) bend and decrease pitch
b) be absorbed and stopped
c) slow down and reflect
d) speed up and refract

C

Explanation:

This is because glass (2400 kg/m^3) is denser than water (1000 kg/m^3).  Water has a refractive index of water is 1.33 while that of glass is 1.54.  This means that because the light is traveling from a medium of lower to higher refractive index, it will slow down and most of it will be reflected back into the water medium.