Lower the refractive index , higher the wave length
Refractive index becoming high reduces the velocity and hence wavelength as frequency remains unchanged.
So refractive index 1.4831 will correspond to wavelength of 450 nm.
For refractive index is 1.4831 , angle of incidence i , angle of refraction r .
Sin i / Sinr = 1.4831
sin65 / sinr = 1.4831
sir r = sin65 / 1.4831
= .9063 / 1.4831
r = 37.67 degree
For refractive index is 1.4754 , angle of incidence i
Sin i / Sinr = 1.4754
sin65 / sinr = 1.4754
sir r = sin65 / 1.4754
= .9063 / 1.4754
r = 37.9 degree
angle between two refracted ray
= 0. 23 degree
i believe the answer is a
because if the tool that you are using is not balanced it there would be false mass.