For a prescription of ibuprofen 10% cream, how much ibuprofen is required to make 20 gm of the cream?

To determine how much ibuprofen is required to make 20 gm of a 10% cream, it's important to understand how percentage concentrations work in pharmaceutical formulations.

A 10% concentration means that there are 10 grams of the active ingredient (in this case, ibuprofen) in every 100 grams of the cream. Since the total mass of the cream you want to prepare is 20 grams, you can set up a proportion to find the amount of ibuprofen needed.

To calculate the amount, use the following formula:

[

\text{Amount of active ingredient} = \left( \frac{\text{percentage}}{100} \right) \times \text{total mass of cream}

]

Plugging in the numbers:

[

\text{Amount of ibuprofen} = \left( \frac{10}{100} \right) \times 20 \text{ gm} = 2 \text{ gm}

]

This calculation shows that to make 20 grams of a 10% ibuprofen cream, you will need 2 grams of ibuprofen. This aligns perfectly with the computed requirements based on the percentage concentration formula, confirming the correct answer.

By using the concept of percentage concentration,