Why does the ball disappear when a glass ball is dipped in glycerin?

Why does the ball disappear when a glass ball is dipped in glycerin?

Answer: When a glass ball is immersed in glycerin, the ball is no longer visible. This is because glass and glycerin have the same refractive index. Both behave like homogeneous mediums. There is no reflection or refraction of light rays under their diffraction. So glass cannot be seen separately in glycerine.