0.5 grams of sodium chloride is dissolved to make 0.05 liters of solution. how do i solve this?

If you are trying to find the molarity of this solution you first need to find the number of moles of sodium chloride that are present in the 0.5g sample.  To do this you need to divide the mass of sodium chloride (0.5g) by its molar mass (58.45g/mol) to get 0.00855mol of sodium chloride.  Then you divide the number of moles (0.00855mol) by the volume of solution (0.05L) to get 0.171M (The units for molarity is mol/L).  Therefore the solution has a concentration of 0.171M.

I hope this helps.  Let me know in the comments if anything was unclear or if you were asking a different question.

Density and pressure

Is a logical series of steps