Question 66

The final percentage strength of the drug is 6.67%

When 500 mL of a 20% (v/v) solution is diluted to a total volume of 1500 mL, the final percentage strength of the drug is calculated to be 6.67%.

A) 1.77%

This option is incorrect. A 1.77% concentration would imply that a significantly lower amount of the active substance is present in the final solution compared to the initial concentration. The dilution of 500 mL of a 20% solution to 1500 mL does not lead to such a low concentration.

B) 3.23%

This option is also incorrect. A 3.23% concentration suggests a higher concentration than what would result from diluting the initial 20% solution to 1500 mL. The calculation shows that the final concentration is not as low as 3.23%.

C) 6.67%

This option is correct. When diluting a 20% solution to a larger volume, the concentration is reduced proportionally. The calculation confirms that the concentration of the active ingredient in the final solution is indeed 6.67%.

D) 8.95%

This option is incorrect. An 8.95% concentration does not accurately reflect the dilution process of a 20% solution to 1500 mL. It indicates a concentration that is higher than what is achieved with the given dilution.

Conclusion

The correct answer, 6.67%, accurately reflects the proportional decrease in concentration resulting from the dilution of the original 20% solution. All other options fail to represent the correct concentration after the specified dilution, demonstrating a misunderstanding of the dilution process and its impact on solution strength.