A 13.97 g sample of nabr contains 22.34% na by mass. Considering the law of constant composition (definite proportions) how many grams of sodium does a 5.75 g sample of sodium bromide contain?

As per the law of constant composition, a given sample will always contain the same number of elements that combine in the same mass proportion.

Therefore if a sample of 13.97 g of NaBr contains 22.39 % of Na by mass then, a sample of 5.75 g of NaBr would also contain 22.39% Na by mass

Hence:

Mass of Na = 5.75 g * 22.39/100 = 1.287 g

5.75 g of NaBr would contain 1.29 g of Na