For the same value of angle of incidence, the angles of refraction in three media A, B, and C are 15°, 25°, and 35° respectively. In which medium would the velocity of light be minimum?

Let the refractive index of the medium be n and speed of light in air is c. Using Snell's law of refraction: nair × sin i = nmedium × sin r where nair = 1 ∴ 1 × sin i = n × sin r ⟹ n = sin i / sin r
Velocity of light in a medium v = c/n = c × sin r / sin i ⟹ v ∝ sin r
Thus velocity of light is minimum in medium A.