What is water glass

Water glass is

Water glass is:

Water glass is:

Water glass is :

Water glass is :

Water glass is :

The refractive indices of water and glass are 1.2 and 1.5 respectively. What will be the refractive index of glass with respect to water ?

At the bottom of a trough filled with water a rectangular glass slab is placed. A ray of light is incident on the water surface at an angle of 30^(@) and enters the glass after passing through the water. What is the angle of refraction in glass? Given, refractive index of water is 1.33 and that of glass is 1.5.