Answer
Light emerges at Q if the incident angle at P is increased slightly.
Work Step by Step
If the incident angle at P is increased slightly, then the angle of refraction $\theta_2$ at P also increases.
The incident angle at Q is $90^{\circ}-\theta_2$, and this angle decreases if $\theta_2$ increases.
Then the angle of refraction at Q decreases to an angle less than $90^{\circ}$, and light emerges at point Q.
Light emerges at Q if the incident angle at P is increased slightly.
