Answer:
2.97 g
Step-by-step explanation:
First convert mass to moles.
7.72 g Mg × (1 mol Mg / 24.3 g Mg) = 0.318 mol Mg
Use stoichiometry to find moles of nitrogen.
0.318 mol Mg × (1 mol N₂ / 3 mol Mg) = 0.106 mol N₂
Convert moles to mass:
0.106 mol N₂ × (28.0 g N₂ / mol N₂) = 2.97 g N₂