mass of 50 mL beaker + Nacl = 33.6571g
mass of "empty" 50 mL beaker/g = 32.0753g
mass of NaCl used/g = 1.5818g
Final volume of solution /L= 250mL

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mass of 50 mL beaker + Nacl = 33.6571g
mass of "empty" 50 mL beaker/g = 32.0753g
mass of NaCl used/g = 1.5818g
Final volume of solution /L= 250mL

You're so close already.

How many g L^-1 are in your solution? Therefore how many mol L^-1? (hint: what's the molecular mass?)