Answer:

Explanation:
A right triangle is formed, in which the vertical elevation is the opposite cathetus and the horizontal distance is the adjacent cathetus, since we know these two values, we can calculate the angle of inclination using the definition of tangent:

Answer:
Liquid's index of refraction, n₁ = 1.27
Explanation:
It is given that,
The critical angle for a liquid in air is, 
We have to find the refractive index of the liquid. Critical angle of a liquid is defined as the angle of incidence in denser medium for which the angle of refraction is 90°.
Using Snell's law as :

Here, 

Where
n₂ = Refractive index of air = 1
n₁ = refractive index of liquid
So,


n₁ = 1.269
or n₁ = 1.27
Hence, the refractive index of liquid is 1.27