Question 16

1.5 grams of active ingredient are required.

To determine the amount of active ingredient needed, we use the formula for weight/volume (w/v) concentration, which states that a 5% w/v solution contains 5 grams of solute per 100 mL of solution. Thus, for 30 mL, the calculation yields 1.5 grams.

A) 0.15

This option is incorrect because 0.15 grams would imply that the concentration is significantly lower than 5%, which does not align with the calculation based on the 5% w/v solution.

B) 1.5

This is the correct answer. A 5% w/v solution indicates that there are 5 grams of solute in 100 mL, so in 30 mL, the amount of active ingredient is calculated as (5 grams/100 mL) * 30 mL = 1.5 grams.

C) 15

This option is incorrect as it suggests that the amount required is ten times greater than what is needed. The calculation clearly shows that only 1.5 grams is necessary for the 30 mL of a 5% solution.

D) 150

This option is also incorrect as it indicates an unrealistically high quantity of active ingredient. The conversion from a 5% w/v solution to grams shows that 150 grams is far beyond the requirement for 30 mL.

Conclusion

The correct answer of 1.5 grams is derived directly from applying the concentration formula for a 5% w/v solution. All other options fail to reflect the accurate calculations based on the given concentration, thus reinforcing that B) is the only valid choice in this scenario.