Select the correct statements :

            I) A concave mirror and convex lens both have the same focal length in air. When they are

            submerged in water, they will still have the same focal length.

            II) The refractive index of water is smaller than the refractive index of air.

            III) The formula connecting u, v and f for a spherical mirror is valid only for mirrors whose

            sizes are very small compared to their radii of curvature.

            IV) Laws of reflection are strictly valid for plane surfaces, but not for large spherical surface.