Final answer:
The mass of sodium (Na) present in the NaBr sample is calculated using the mass percent formula, and the result is 3.21g, which corresponds to answer choice a).
Step-by-step explanation:
The student has asked how to calculate the mass of sodium (Na) present in a sample of sodium bromide (NaBr) that has a total mass of 14.39g and contains 22.34% Na by mass.
To find the mass of Na, we use the mass percent formula:
mass of Na = (mass percent of Na/100) × total mass of the sample
mass of Na = (22.34/100) × 14.39g
mass of Na = 3.21g
Therefore, the correct answer is a) 3.21g.