An answer cannot be given without providing the mols of AgNO3 and the volume of the solution.
The molarity of the silver nitrate solution is 0.394 mM.
The balanced chemical equation for this double replacement reaction looks like this
Notice that you have a
The net ionic equation for this reaction is
You know the mass of the potassium chloride sample, which means that you can use the compound's molar mass to determine how many moles of the compound reacted
This is equal to the number of moles of silver nitrate you need in order for the reaction to precipitate all the
Now use the volume of the silver nitrate solution to determine its molarity