Nine grams of pure drug are in 100 ml of solution. What is the percent strength of solution?

1. The percent strength is calculated by taking the mass of the drug and dividing by the total volume of the solution, then multiplying by 100.

P = \left( \frac{m}{V} \right) \times 100

2. For this problem:

m = 9 \, \text{grams}

V = 100 \, \text{ml}

3. Substitute the given values into the formula:

P = \left( \frac{9}{100} \right) \times 100

4. Simplify:

P = 9\%

Therefore, the percent strength of solution is

P = 9\%