$A$ ray incident at ${15^o}$ on one refracting surface of a prism of angle ${60^o}$ suffers a deviation of ${55^o}$. What is the angle of emergence?

$A$ prism $(\mu=1.5)$ has a refracting angle of $30^{\circ}$. The deviation of a monochromatic ray incident normally on one of its surfaces will be (given,$\sin 48^{\circ} 36^{\prime}=0.75$):

The angle of deviation through a prism is minimum when
$(A)$ Incident ray and emergent ray are symmetric to the prism
$(B)$ The refracted ray inside the prism becomes parallel to its base
$(C)$ Angle of incidence is equal to that of the angle of emergence
$(D)$ When angle of emergence is double the angle of incidence
Choose the correct answer from the options given below

$A$ 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 $^{\circ}$)

For a glass prism $(\mu = \sqrt{3})$,the angle of minimum deviation is equal to the angle of the prism. Find the angle of the prism. (in $^{\circ}$)

$A$ thin prism of angle $6^{\circ}$ made of glass of refractive index $1.5$ is combined with another prism made of glass of refractive index $1.75$ to produce dispersion without deviation. Then the angle of the second prism is ...... (in $^{\circ}$)