From the calculations, the percentage by mass of the nitrogen is 18.9 %..
<h3>What is the percentage by mass?</h3>
The term percentage by mass refers to the mass of an atom that is contained in a compound.
Hence, the compound magnesium nitrate has the formula Mg(NO3)2. The molar mass of the compound is 24 + 2(14 + 3(16)) = 148 g/mol.
The percentage by mass of nitrogen is; 28/ 148 * 100/1 = 18.9 %.
Learn more about percentage by mass:brainly.com/question/16885872
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