page 14 18. A ray of monochromatic light passes from air into water. The wavelength of this light in air is 589 nm. The speed of this light in water is A 2·56 × 102 m s−1 B 4·52 × 102 m s−1 C 2·26 × 108 m s−1 D 3·00 × 108 m s−1 E 3·99 × 108 m s−1. 19. When light passes through the outer layers of the Sun certain frequencies of light are absorbed by hydrogen atoms, producing dark lines in the spectrum. The diagram represents some of the energy levels for a hydrogen atom. E0 E1 E2 E3 E4 The number of absorption lines in the spectrum caused by the transition of electrons between these energy levels is A 4 B 6 C 9 D 10 E 20.