Answer:
Between 120 and 180 seconds
Common symbol of the volume (L)
Answer:

Explanation:
The refractive index of a medium is a measure to know how much the speed of light within the medium is reduced. It can be calculated with the next equation:
(1)
Where:


The speed of light in the vacuum is approximately 300,000 km/s. In order to work with the same units let's do the proper conversion with the velocity of the medium:

Finally, replacing the data in (1):

I am pretty sure the answer to your question is B