Final answer:
The weight/volume percentage concentration of the KCl solution is calculated by dividing the mass of KCl by the volume of water and then multiplying by 100%, resulting in a concentration of 22.50%.
Step-by-step explanation:
To calculate the weight/volume percentage concentration of a solution, we use the formula: Percent concentration = (mass of solute in grams / volume of solution in liters) × 100%. In this instance, we have 45.0 grams of potassium chloride (KCl) dissolved in 2.0 liters of water. Applying the formula, we get:
Percent concentration = (45.0g / 2.0L) × 100% = 22.50%
Therefore, the weight/volume percentage concentration of the KCl solution is 22.50%, which aligns with option C.