Answer:
20.9%
Explanation:
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Taking into account the definition of molarity, the concentration of the solution is 0.855
.
<h3>Definition of molarity</h3>
Molar concentration or molarity is a measure of the concentration of a solute in a solution and indicates the number of moles of solute that are dissolved in a given volume.
The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution:

Molarity is expressed in units
.
<h3>Molarity of NaCl</h3>
In this case, you have:
- number of moles of NaCl=
1.71 moles (being 58.45 g/mole the molar mass of NaCl) - volume 2 L
Replacing in the definition of molarity:

Solving:
Molarity= 0.855 
Finally, the concentration of the solution is 0.855
.
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Answer:
2x + 3y = 18 sum of charges of the iron ions must be +18 to balance 18 CN- ... y = 4 so there are 4 Fe3+ ions and (7–4) = 3