Which of the following ray diagrams shows physically possible refraction?

$A$ ray of light is incident at an angle $i$ on a glass slab of refractive index $\mu$. The angle between the reflected and refracted light is $90^{\circ}$. Then, the relationship between $i$ and $\mu$ is

$A$ ray of light passes from the vacuum into a medium of refractive index $n$. If the angle of incidence is twice the angle of refraction, then the angle of incidence in terms of refractive index is

If ${ }_{i} \mu_{j}$ represents the refractive index when a ray goes from medium $i$ to medium $j$,then the product ${ }_2 \mu_1 \times { }_3 \mu_2 \times { }_4 \mu_3$ is equal to:

When light enters from air to water,then its

$A$ ray of light is incident at the glass-water interface at an angle $i$. It emerges finally parallel to the surface of water. If the refractive index of water is $\mu_w = 4/3$,then the value of the refractive index of glass $\mu_g$ is: