Answer: 1.333
Explanation:
Index of refraction= n=c/v
Where c is the speed of light in vacuum and v is the speed of light in material ( water) in this case.
n = 3.00.108/2.25.108
n =3.00/2.25
n = 1.333
Approximately 1.33
There is no unit because m/s cancels out m/s