Concerning the 10.0 ml of 0.50 m nacl to 100 ml of solution:
does dilution change the concentration?

yes
no

Yes

Explanation:

Before dilution:

Volume of NaCl = 10 mL

Concentration of NaCl = 0.5 M

Number of moles = Molarity*Volume = 0.5*10 = 5 millimoles.

Note that number of moles of NaCl does not change on dilution as we are only adding water.

After dilution:

Volume of NaCl = 100 mL

Number of moles = 5 millimoles (no change)

New Concentration = Number of moles per volume in litres = = 0.05 Molar

Hence the concentration became one-tenth of the initial concentration after dilution.

explanation: