The final concentration of NaCl will be 0.04 mol/L.
The dilution principle states that the number of moles of solute in a diluted solution remains the same as before dilution.
Mathematically, m1v1=m2v2
In this case, m1 = 0.4 mol/L, v1 = 1 mL, v2 = 1+9 = 10 mL
m2 = m1v1/v2 = 0.4 x 1/10 = 0.04 mol/L
Thus, the final concentration of the NaCl solution will be 0.04 mol/L.
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