Determine the percentage strength of a solution containing 20 grams of drug in 300ml.

To calculate the percentage strength of a solution, you can use the formula for percentage strength, which is:

[

\text{Percentage Strength} = \left( \frac{\text{mass of solute (g)}}{\text{volume of solution (ml)}} \right) \times 100

]

In this case, you have a solution containing 20 grams of the drug in 300 milliliters of solution. Plugging the values into the formula gives:

[

\text{Percentage Strength} = \left( \frac{20 , \text{g}}{300 , \text{ml}} \right) \times 100

]

Calculating the fraction:

[

\frac{20}{300} = 0.0667

]

Now, multiply this by 100 to convert it into a percentage:

[

0.0667 \times 100 = 6.67%

]

Thus, the percentage strength of the solution is 6.67%. This makes the choice of 6.67 the correct answer. Understanding this calculation is essential as it helps pharmacy technicians assess and prepare solutions accurately, an important skill in medication preparation.