Light speed in water is 2.25 times 10^5 m/s so the index of refraction is higher than the index of refraction of light in a vacuum which is 1.0. (speed in vacuum for light is 300,000 km/s)
Index of refraction of light in water is 3.0 time 10^5 m/s divided by 2.25 times 10^5 m/s = 1.33.
A photoautotroph get its energy and carbon from the sunlight and from organic material. Photoautotrophs are organisms that carry out photosynthesis. They use energy from sunlight to carry out cellular processes. Hope this answers the question.
