Internal standard. A solution was prepared by mixing 10.00 mL of unknown (X) with 5.00 mL of standard (S) containing 8.24 μg S/mL and diluting the mixture to 50.0 mL. The measured signal quotient was (signal due to X/signal due to S)1.690/1.000. In a separate experiment, in which the concentrations of X and S were) equal, the quotient was (signal due to, x/signal due to S) 0.930/1.000. What is the concentration of X in the unknown?