The speed of light in water is 2.25 x 108 m/s. what is true about the index of refraction of water?

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.

Hope this is what you wanted.