Given:

Mass Percent of iodine = 10 %

Mass of solution, W = 50 gm

To Find:

The amount of solvent needed to prepare the given solution.

Calculation:

- Tincture of iodine is the solution of iodine in a mixture of ethanol and water. It is used as a tincture of iodine.

- Mass percent is given as:

w/w % = (w/W) × 100

⇒ 10 = (w/50) × 100

⇒ w = 5 gm

⇒ Amount of solvent = W - w = 50 - 5 = 45 gm

- So, the amount of solvent, i.e., Ethanol and Water, is 45 grams.