Answer : The number of Fe(II) ions present are

Explanation : Given,
Mass of
= 15.0 g
Molar mass of
= 152 g/mole
First we have to calculate the moles of


Now we have to calculate the number of Fe(II) ions.
In
, there 1 atom of iron ion and 1 atom of sulfate ion.
As we know that,
1 mole of substance always contains
number of atoms or ions.
As, 1 mole of
contains
number of Fe(II) ions.
So, 0.0987 mole of
contains
number of Fe(II) ions.
Therefore, the number of Fe(II) ions present are
