Which of the following prisms is used to see the infrared spectrum of light?

When white light passes through an achromatic combination of prisms,what is observed?

The principal section of a glass prism is an isosceles triangle $ABC$ with $AB = AC$. The face $AC$ is silvered. $A$ ray of light is incident normally on the face $AB$ and after two reflections, it emerges from the base $BC$ perpendicular to the base. The angle $BAC$ of the prism is: (in $^{\circ}$)

$A$ plane polarized blue light ray is incident on a prism such that there is no reflection from the surface of the prism. The angle of deviation of the emergent ray is $\delta=60^{\circ}$ (see Figure-$1$). The angle of minimum deviation for red light from the same prism is $\delta_{\text{min}}=30^{\circ}$ (see Figure-$2$). The refractive index of the prism material for blue light is $\sqrt{3}$. Which of the following statement$(s)$ is(are) correct?
$(A)$ The blue light is polarized in the plane of incidence.
$(B)$ The angle of the prism is $60^{\circ}$.
$(C)$ The refractive index of the material of the prism for red light is $\sqrt{2}$.
$(D)$ The angle of refraction for blue light in air at the exit plane of the prism is $60^{\circ}$.

For an equilateral prism,the angle of incidence and the angle of emergence are each equal to $3/4$ of the prism angle. The angle of deviation is .......... $^o$.

If the refractive angles of two prisms made of crown glass are $10^o$ and $20^o$ respectively,then the ratio of their angular dispersions will be