Dont know the first part but melanin quantities change the dkin color
Answer:
Hb would be 78.4% saturated.
Explanation:
This problem can be solved by using simple unitary method.
At 100 mm Hg pressure of oxygen, Hb is saturated by 98%
So, at 1 mm Hg pressure of oxygen, Hb is saturated by 
%
Hence, at 80 mm Hg pressure of oxygen, Hb is saturated by 
% or 78.4%
Therefore, at 80 mm Hg pressure of oxygen in the lungs, Hb would be 78.4% saturated.
Well, the only way you would get clouds is evaporation, a liquid to a gas. (Change of matter) the clouds would not turn into rain without percipitation, gas to water. (Change of matter.)
The correct option is this: THE CONCENTRATION OF THE PRODUCTS AND THE REACTANTS DO NOT CHANGE.
A reversible chemical reaction is said to be in equilibrium if the rate of forward reaction is equal to the rate of backward reaction. At this stage, the concentrations of the products and the reactants remain constant, that is, there is no net change in the concentration even though the reacting species are moving between the forward and the backward reaction.
