Answer:
[tex]Concentration=0.11\ mmol/L}[/tex]
Explanation:
Given that:-
Moles of the salt, [tex]NiCl_2[/tex] = 21 μmol
Also, 1 μmol = 0.001 mmol
So,
Moles = 0.021 mmol
Given that:- The volume = 200 mL
Also, 1 mL = 0.001 L
So, Volume = 0.2 L
Thus,
[tex]Concentration=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}[/tex]
[tex]Concentration=\frac{0.021\ mmol}{0.2\ L}[/tex]
[tex]Concentration=0.11\ mmol/L}[/tex]