Final answer:
The mass of the substance in an 18.04 mL solution with a 4.56% concentration is calculated using the percentage concentration formula, resulting in 0.822624 grams.
Step-by-step explanation:
To calculate the mass (m1) of the substance in the 4.56% stock solution utilized by a student, we use the percentage concentration formula: % mass = (mass of solute / volume of solution) x 100. Given a volume (V1) of 18.04 mL and a stock solution concentration of 4.56%, we rearrange the formula to solve for m1: m1 = (% mass / 100) x V1.
We plug in the values as follows: m1 = (4.56 / 100) x 18.04 mL = 0.822624 grams. Therefore, the correct answer is (a) 0.822624 grams.