The concentration of HCl is equal to 2.54mol/L.
To solve this question, one must use the molarity calculation, which corresponds to the following expression:
[tex]M = \frac{mol}{v}[/tex]
Thus, to find the molarity of the sample, the following calculations must be performed:
[tex]V_f = 10ml + 625ml = > 635ml[/tex]
[tex]\frac{0.004mol}{xmol} =\frac{1000ml}{635ml}[/tex]
[tex]x = 0.00254 mol[/tex]
So, 0.00254 moles were added per 10ml, so we can do:
[tex]\frac{0.00254mol}{xmol}= \frac{10ml}{1000ml} \\x = 2.54mol/L[/tex]
So, the concentration of HCl is equal to 2.54mol/L.
Learn more about mole calculation in: brainly.com/question/2845237