Question

Condition for light not coming through prism

Answer 1

The prism is not of transparent glass but of any other opaque material will not disperse or scatter the white light into constituent colours because refraction needs only two different transparent media to occur.

Answer 2

The condition for no emergence for any value of incident angle
$(0 \leqslant i \leqslant 90)$
is that the angle of refraction at the first surface should be equal to the critical angle.