A 10.0 mL sample of a 2.5 M NaCl solution is diluted to 25.8 mL. What is the new concentration?

Explanation:

Hello,

In this case, for dilution process, we can notice that the initial moles remain the same once the dilution is completed, therefore, both concentration and volume change considering:

In such a way for the given final volume, the resulting concentration is noticed to be:

This is supported by the fact that the higher the volume the lower the concentration.

Best regards.

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.