A light ray is travelling between two media as given below. The angle of incidence on the boundary in all the cases is ${30}^0$
Identify the correct sequence of increasing order of angles of refraction, 
a) Air to water  
b) Water to glass 
c) Glass to water (Refractive indices of glass and water are respectively 3/2 and 4/3)

In case (i), ray travels from air (rarer) to water (denser) medium, so it bends towards the normal.
In case (ii), ray travels from water (less rarer than air) to glass (denser), so it bends (less as in case (i)) towards the normal.
In case (iii), ray travels from glass (denser) to water (rarer), so it bends away from the normal. Hence, correct sequence will be (a).