What is the index for a type of oil if light has a velocity of 2.5 x 10^(8) m/s in this
substance?

1.2

Explanation:

Data obtained from the question include:

Velocity of light in the oil (V) = 2.5x10^8m/s

Velocity of light in air (C) = 3x10^8m/s

Refractive Index (n) =.?

The rafractive index (n) for the oil is given by:

Rafractive index (n) = Velocity in air (V) /velocity in oil (V)

n = C/V

n = 3x10^8 / 2.5x10^8

n = 1.2

Therefore, the Refractive Index of the oil is 1.2.

hypothesising or postulating