16 molar.

It is not true, they are not identical.

The Stoichiometry of molar concentration follows this simple formula:

Mol = Volume (dm³) × Molar Concentration (mol/dm³)

Hence: Molar Concentration (mol/dm³) = Number of moles (mol)/ Volume (dm³)

Not necessarily or even usually. The term "one molar" refers to the concentration of the acid added and does not have anything to do with the concentration of ferrous ions.

Molar absorptivity is completely independent of concentration of a substance as Molar absorptivity is represented by epsilon and is a constant. Absorbance of light is what is dependent upon concentration and will go down as concentration goes down and increase as concentration increases.