The variation of the refractive index of a crown glass thin prism with the wavelength of the incident light is shown. Which of the following graphs is the correct one,if $D_m$ is the angle of minimum deviation?

The refracting angle of a prism is $A,$ and the refractive index of the material of the prism is $\cot(A/2).$ The angle of minimum deviation is:

$A$ 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 $P_1$ with angle $4^o$ made of glass of refractive index $1.54$ is combined with another thin prism $P_2$ made of glass of refractive index $1.72$ to produce no deviation. The angle of prism $P_2$ is.....$^o$

The refractive index $(R.I.)$ of a prism is $\sqrt{\frac{7}{3}}$ and the angle of the prism is $60^{\circ}$. The limiting angle of incidence of a ray that will be transmitted through the prism is .....$^{\circ}$

$A$ small-angled prism is made of a material of refractive index $\frac{3}{2}$. The ratio of the angles of minimum deviation when the prism is placed in air and in water of refractive index $\frac{4}{3}$ is: