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

In an equilateral prism,the ray undergoes minimum deviation when it is incident at an angle of $50^{\circ}$. The angle of minimum deviation is (in $^{\circ}$)

Obtain the relation between incidence angle,emergence angle,prism angle,and deviation angle for refraction through a prism.

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

If the angle of minimum deviation of a prism is $30^o$,the angle of incidence is $60^o$,and the prism angle is $30^o$,then the refractive index of the prism is:

$A$ prism of crown glass with a prism angle of $9^{\circ}$ and a prism of flint glass are used to make a direct vision spectroscope. If the refractive indices of crown and flint glass are $1.40$ and $1.60$ respectively,then the refracting angle of the flint glass prism will be.....$^{\circ}$