What is the concentration of agcl in an aqueous solution that contains 1.2x10-3 gram of agcl in 800.grams of the solution

Given that you only know the mass in grams of the solute and the mass in grams of the solution, you can only calculate the concentration as percent mass/mass.

The formula is:

Percent m/m, % = [ (mass in grams of solute) / (mass in grams of solution) ] * 100

% = [ (1.2 * 10^ -3 g) / (800 g) ] * 100 = 0.0015%

0.0015%

The answer is 65.3312