Answer:
1) Recollapsing universe
2) critical universe
3) Coasting universe
Explanation:
According to the smallest ration (ratio actual mass density to current density) to largest ration, rank of models for expansion of universe are
1) Recollapsing universe -in this, metric expansion of space is reverse and universe recollapses.
2) critical universe - in this, expansion of universe is very low.
3) Coasting universe - in this, expansion of universe is steady and uniform
The answer is B. Sunlight (white light) refracts when it passes through droplets of water in the atmosphere
To solve this problem it is necessary to apply the concepts related to the condition of path difference for destructive interference between the two reflected waves from the top and bottom of a surface.
Mathematically this expression can be described under the equation

Where
n = Refractive index
t = Thickness
In terms of the wavelength the path difference of the reflected waves can be described as

Where
\lambda = Wavelenght
Equation the two equations we have that


Our values are given as
Wavelength of light



Therefore the minimum thickness of the oil for destructive interference to occur is approximately 34.0 nm