The refractive index of a material is a measure of how light bends when it enters that material. It is defined as the ratio of the speed of light in a vacuum or air to the speed of light in that material.

In this question, the refractive index of crown glass is given as close to 3/2. This means that when light enters crown glass, it slows down compared to its speed in air.

To find the speed of light in the crown glass, we can use the formula:

Speed of light in crown glass = (Speed of light in air) / (Refractive index of crown glass)

Option 1 states that the speed of light in the crown glass will be (3/2)c, which means 1.5 times the speed of light in air.

Option 2 states that the speed of light in the crown glass will be (4/9)c, which is not correct according to the provided refractive index.

Option 3 states that the speed of light in the crown glass will be (2/3)c, which is the correct answer based on the given refractive index.

Option 4 states that the speed of light in the crown glass will be (9/4)c, which is