Answer:
n = 1.56
Explanation:
The total reflection attempts occurs when a light beam passes from a medium with a higher index to a medium with a lower nest, at an angle where it occurs we can find them by the refractive relationship
n₁ sin θ₁ = n₂ sin θ₂
n1 = n2 / sin θ₁
For this relationship to be fulfilled, the liquid index must be greater than the air index divided by the sine of the critical angle
Let's use trigonometry to find angle
tan θ = y / x
θ = tan⁻¹ 7.2 / 8.6
θ = 39.94º
n₁ = 1 / sin 39.94
n = 1.56
This is the refractive index of the liquid