A light ray emerging from the point source placed at P(2,3) is reflected at a point Q on the y-axis. It then passes through the point R(5, l0). The coordinates of Q are

The point of coincidence on  the y -axis is Q(0,λ) . The image of P(2,3) on the y -axis is P1(−2,3)Therefore,  Slope of P1Q= Slope of P1R or  λ−30−(−2)=10−35−(−2) or     λ−3=2 or     λ=5Therefore, the point Q is (0, 5).