Is the statement "Angle made by the incident ray with the reflecting surface is the angle of incidence" correct?

$A$ beam of initially parallel cylindrical light rays travels in a medium with a refractive index $\mu(I) = \mu_0 + \mu_2 I$,where $\mu_0$ and $\mu_2$ are positive constants and $I$ is the intensity. As the intensity of the beam decreases with radius,the speed of light in the medium is:

The frequency of a light wave in a material is $2 \times 10^{14} \ Hz$ and its wavelength is $5000 \ \mathring{A}$. The refractive index of the material will be:

The refractive index of air with respect to vacuum is . . . . . . .

$A$ ray of light is incident at an angle of $75^{\circ}$ into a medium having refractive index $\mu$. The reflected and the refracted rays are found to suffer equal deviations in opposite directions. The value of $\mu$ is:

The distance travelled by light in glass (refractive index $= 1.5$) in a nanosecond will be.......$cm$.