A ray of light is incident on a plane mirror at an angle of ${30}^{\circ }$ with the mirror. What is the angle between the incident and the reflected ray?

The correct option is B ${120}^{\circ }$
As the ray of light is incident on a plane mirror at an angle of ${30}^{\circ }$ with the mirror, the angle of incidence is equal to the angle of reflection, i.e., ${60}^{\circ }$.

Therefore, the angle between the incident and the reflected ray will be:
${60}^{\circ }+{60}^{\circ }={120}^{\circ }$