Refractive Index: 1.4465

Refractive index of vacuum is 1.

Refractive Index: 2.4175-2.4178

"The refractive index of water is 4 / 3" means the refractive index of water with respect to air. "The refractive index of glass is 3 /2" means the refractive index of glass with respect to air.

You change the question as ," what is the refractive index of glass with respect to water?

The answer is it is the ratio of refractive index of of glass with respect to air to the refractive index of water with respect to air =( 3/2) divided by( 4/3) = 1.125

I assume "molecular refractive index" refers to "the refractive index of a group of molecules". In this case, you just use the units for a refractive index - i.e., a dimensionless number.