At what angle will a ray of light be incident on one face of an equilateral prism,so that the emergent ray may graze the second surface of the prism $(\mu=2)$ (in $^{\circ}$)?

$A$ thin prism with angle $5^{\circ}$ and refractive index $1.72$ is combined with another prism of refractive index $1.9$ to produce dispersion without deviation. The angle of the second prism is . . . . . . . (in $^{\circ}$)

$A$ thin prism in air produces the angle of minimum deviation $\delta$. If the prism is immersed in water, the angle of minimum deviation for the same ray is (refractive index of water is $4/3$ and that of glass prism is $3/2$)

For refraction through a small angled prism,the angle of deviation:

It was found that the refractive index of the material of a certain prism varied as $\mu = 1.5 + 0.004 / \lambda^{2}$,where $\lambda$ is the wavelength of light used to measure the refractive index. The same material was then used to construct a thin prism of apex angle $10^{\circ}$. Angles of minimum deviation $\delta_{m}$ of the prism were recorded for the sources with wavelengths $\lambda_{1}$ and $\lambda_{2}$,respectively. Then,

On an equilateral prism,it is observed that a ray strikes grazingly at one face and if the refractive index of the prism is $2$,then the angle of deviation is $........^o$.