To find the ratio of drug molecules to the number of cancer cells in the dish, we need to first calculate the number of drug molecules in 5.00 mL of the drug solution.
First, we convert the concentration of the drug solution from Molarity to molecules per liter:
1.5 x 10^-9 mol/L = 1.5 x 10^-9 x 6.022 x 10^23 molecules/L = 9.033 x 10^14 molecules/L
Next, we calculate the number of drug molecules in 5.00 mL of the drug solution:
9.033 x 10^14 molecules/L x 0.005 L = 4.5165 x 10^12 molecules
Now, we calculate the ratio of drug molecules to the number of cancer cells in the dish:
4.5165 x 10^12 molecules / 2.0 x 10^5 cells = 2.25825 x 10^7 molecules per cell
Therefore, the ratio of drug molecules to the number of cancer cells in the dish is approximately 2.26 x 10^7 molecules per cell.