y, p, z
p, y, z
p, z, y
x, q, z
It is clear from the diagram,
Angle of incidence=p
The angle of incidence is the angle between the incident ray and the normal.
Angle of emergence=y
The angle of emergence is the angle between the angle between the emergent ray and the normal.
And Angle of deviation=z
The Angle of emergence is angle between the incident ray and the emergence ray.
So the proper sequence is p,y,z